Boost: Package Update

Boost.Context Fix:
 - The Boost.Coroutine2 lib requires Boost.Context to be compiled using the
   standard C++14. [1]

[1]: https://bugs.archlinux.org/task/48779

Signed-off-by: Carlos M. Ferreira <carlosmf.pt@gmail.com>

libs/boost/Makefile

@@ -17,7 +17,7 @@ include $(INCLUDE_DIR)/target.mk
 
 PKG_NAME:=boost
 PKG_VERSION:=1_60_0
-PKG_RELEASE:=1
+PKG_RELEASE:=2
 
 PKG_SOURCE:=$(PKG_NAME)_$(PKG_VERSION).tar.gz
 PKG_SOURCE_URL:=@SF/boost
@@ -336,7 +336,7 @@ comma := ,
 define Build/Compile
 	$(info Selected Boost API $(BOOST_ABI) for architecture $(ARCH) and cpu $(CPU_TYPE) $(CPU_SUBTYPE))
 	( cd $(PKG_BUILD_DIR) ; \
-		echo "using gcc : $(ARCH) : $(GNU_TARGET_NAME)-gcc : <compileflags>\"$(TARGET_CFLAGS)\" <cxxflags>\"$(TARGET_CXXFLAGS)\" <linkflags>\"$(TARGET_LDFLAGS)\" ;" > tools/build/src/user-config.jam ; \
+		echo "using gcc : $(ARCH) : $(GNU_TARGET_NAME)-gcc : <compileflags>\"$(TARGET_CFLAGS)\" <cxxflags>\"$(TARGET_CXXFLAGS) $(if $(CONFIG_boost-coroutine2),-std=c++14,)\" <linkflags>\"$(TARGET_LDFLAGS)\" ;" > tools/build/src/user-config.jam ; \
 		$(if $(CONFIG_PACKAGE_boost-python3), \
 			echo "using python : 3.5 : $(STAGING_DIR_ROOT)/usr/bin/python3 : $(STAGING_DIR)/usr/include/python3.5/ ;" >> \
 				tools/build/src/user-config.jam; \