boost: add host library build for boost

Summary: Currently, boost host build doesn't actually compile boost
libraries for the host arch. If there are host tools that would want
to link against boost, it can't right now.

This diff adds support for compiling host boost library as well.
Any packages that need to depend on a host boost library can depend on
CONFIG_boost-host-build-<lib>.

Test Plan: Compiled fbthrift and verified that it works.
used openwrt master using nbg6817

Maintainer: @ClaymorePT

Signed-off-by: Amol Bhave <ambhave@fb.com>

libs/boost/Makefile

@@ -3,7 +3,7 @@
 # See /LICENSE for more information.
 #
 
-# 
+#
 # Original Boost 1.51 Makefile by Mirko Vogt <mirko@openwrt.org>
 # Dude, this "boost" is really one of the most crude stuff I ported yet.
 #
@@ -13,7 +13,7 @@ include $(TOPDIR)/rules.mk
 PKG_NAME:=boost
 PKG_VERSION:=1.70.0
 PKG_SOURCE_VERSION:=1_70_0
-PKG_RELEASE:=4
+PKG_RELEASE:=5
 
 PKG_SOURCE:=$(PKG_NAME)_$(PKG_SOURCE_VERSION).tar.bz2
 PKG_SOURCE_URL:=@SF/$(PKG_NAME)/$(PKG_NAME)/$(PKG_VERSION) https://dl.bintray.com/boostorg/release/$(PKG_VERSION)/source/
@@ -57,7 +57,7 @@ This package provides the following run-time libraries:
  - chrono
  - container
  - context
- - contract 
+ - contract
  - coroutine (Deprecated - use Coroutine2)
  - - coroutine2 (Requires GCC v5 and up)
  - date_time
@@ -142,17 +142,17 @@ define Package/boost/config
 						 cannot be redefined by another shared library or executable. This mode is
 						 not supported on some platforms, for example OS X.
 					-> Hidden:
-						- Hidden symbols are not exported from shared libraries and cannot be 
+						- Hidden symbols are not exported from shared libraries and cannot be
 						 redefined by a different shared library or executable loaded in a process.
 						 In this mode, public symbols have to be explicitly marked in the source code
 						 to be exported from shared libraries. This is the recommended mode.
 
 			config boost-compile-visibility-global
 				bool "Global"
-			
+
 			config boost-compile-visibility-protected
 				bool "Protected"
-			
+
 			config boost-compile-visibility-hidden
 				bool "Hidden"
 		endchoice
@@ -171,10 +171,10 @@ define Package/boost/config
 
 			config boost-shared-libs
 				bool "Shared"
-			
+
 			config boost-static-libs
 				bool "Static"
-			
+
 			config boost-static-and-shared-libs
 				bool "Both"
 		endchoice
@@ -189,7 +189,7 @@ define Package/boost/config
 					- Not available if Shared libs are to be built.
 				-> Use both runtimes.
 					- Not available if Shared libs are to be built.
-					- Two separate versions of Boost are built, linking each to a different runtime. 
+					- Two separate versions of Boost are built, linking each to a different runtime.
 					- This option requires "Use tagged names" option to be active.
 
 			config boost-runtime-shared
@@ -197,7 +197,7 @@ define Package/boost/config
 
 			config boost-runtime-static
 				depends on @(!boost-shared-libs&&!boost-static-and-shared-libs)
-				bool "Static"		    	
+				bool "Static"
 
 			config boost-runtime-static-and-shared
 				depends on @(boost-use-name-tags&&!boost-shared-libs&&!boost-static-and-shared-libs)
@@ -211,7 +211,7 @@ define Package/boost/config
 				Chooses which boost variant should be selected:
 				-> Release: Optimizes Boost for release.
 					- Optimization: Speed;  Debug Symbols: Off; Inlining: Full; Runtime Debugging: Off.
-				-> Debug: 
+				-> Debug:
 					- Optimization: Off; Debug Symbols: On; Inlining: Off; Runtime Debugging: On.
 				-> Profile:
 					- Profiling: On;  Debug Symbols: On.
@@ -228,7 +228,7 @@ define Package/boost/config
 
 		config boost-use-name-tags
 			bool "Use tagged names."
-			help 
+			help
 				Add name tags the lib files, to diferentiate each library version:
 				  "-mt" for multi-threading.
 				  "-d" for debugging.
@@ -239,14 +239,14 @@ define Package/boost/config
 		config boost-single-thread
 			depends on @boost-use-name-tags
 			bool "Single thread Support."
-			help 
+			help
 				Compile Boost libraries in single-thread mode.
 			default n
-			    
+
 		config boost-build-type-complete
 			depends on @boost-use-name-tags
 			bool "Complete Boost Build."
-			help 
+			help
 				Builds both release and debug libs. It will take much longer to compile.
 			default n
 	endmenu
@@ -294,6 +294,16 @@ define Package/boost/config
 		)
 	endmenu
 
+	menu "Select Boost libraries for Host build"
+		comment  "Libraries for Host build"
+
+		$(foreach lib,$(BOOST_LIBS), \
+		config boost-host-build-$(lib)
+			bool "Boost $(lib) $(if $(findstring python,$(lib)),$(paren_left)v$(if $(findstring 3,$(lib)),$(BOOST_PYTHON3_VER),$(BOOST_PYTHON_VER))$(paren_right) ,)library."
+			default n
+		)
+	endmenu
+
 endef
 
 PKG_CONFIG_DEPENDS:= CONFIG_PACKAGE_boost-test
@@ -316,6 +326,7 @@ define DefineBoostLibrary
 
   BOOST_DEPENDS+= +$(if $(4),$(4):boost-$(1),boost-$(1))
   PKG_CONFIG_DEPENDS+= CONFIG_PACKAGE_boost-$(1)
+  HOST_CONFIG_DEPENDS+= CONFIG_boost-host-build-$(1)
 
   BOOST_LIBS+= $(1)
 
@@ -366,6 +377,14 @@ include $(INCLUDE_DIR)/host-build.mk
 define Host/Compile
 	# b2 does not provide a configure-script nor a Makefile
 	( cd $(HOST_BUILD_DIR)/tools/build/src/engine ; ./build.sh gcc )
+
+	( cd $(HOST_BUILD_DIR) ; \
+		./bootstrap.sh --prefix=$(STAGING_DIR_HOST) \
+			--with-libraries=$(subst $() $(),$(comma),$(strip \
+				headers \
+				$(foreach lib,$(BOOST_LIBS), \
+					$(if $(findstring python,$(lib)),,$(if $(CONFIG_boost-host-build-$(lib)),$(lib)))))) ; \
+		./b2 install )
 endef
 
 CONFIGURE_PREFIX:=$(PKG_INSTALL_DIR)
@@ -524,7 +543,7 @@ endef
 
 define BuildBoostLibrary
   define Package/boost-$(1)/install
-    $(call Package/boost/Default/install,$$(1),$(1)) 
+    $(call Package/boost/Default/install,$$(1),$(1))
   endef
 
   $$(eval $$(call BuildPackage,boost-$(1)))