libgflags: add gflags package

Google's gflags library is a C++ library that implements command line
flags processing. Adding the library so that it can used when compiling
other C++ programs.

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

libs/libgflags/Makefile

@@ -0,0 +1,46 @@
+include $(TOPDIR)/rules.mk
+
+PKG_NAME:=gflags
+PKG_VERSION:=2.2.2
+PKG_RELEASE:=1
+
+PKG_SOURCE:=$(PKG_NAME)-$(PKG_VERSION).tar.gz
+PKG_SOURCE_URL:=https://codeload.github.com/gflags/gflags/tar.gz/v$(PKG_VERSION)?
+PKG_HASH:=34af2f15cf7367513b352bdcd2493ab14ce43692d2dcd9dfc499492966c64dcf
+
+PKG_LICENSE:=BSD-3-Clause
+PKG_LICENSE_FILE:=COPYING.txt
+
+include $(INCLUDE_DIR)/package.mk
+include $(INCLUDE_DIR)/host-build.mk
+include $(INCLUDE_DIR)/cmake.mk
+
+PKG_BUILD_PARALLEL:=1
+HOST_BUILD_PARALLEL:=1
+CMAKE_OPTIONS:= \
+	-DGFLAGS_BUILD_SHARED_LIBS=ON \
+	-DGFLAGS_BUILD_STATIC_LIBS=ON
+CMAKE_INSTALL:=1
+
+define Package/gflags
+	SECTION:=libs
+	CATEGORY:=Libraries
+	TITLE:=C++ library that implements commandline flags processing
+	DEPENDS:=+libstdcpp +libpthread
+	URL:=https://github.com/gflags/gflags
+	MAINTAINER:=Amol Bhave <ambhave@fb.com>
+endef
+
+define Package/gflags/description
+	The gflags package contains a C++ library that implements commandline flags
+	processing. It includes built-in support for standard types such as string and
+	the ability to define flags in the source file in which they are used.
+endef
+
+define Package/gflags/install
+	$(INSTALL_DIR) $(1)/usr/lib
+	$(INSTALL_DATA) $(PKG_INSTALL_DIR)/usr/lib/libgflags.so* $(1)/usr/lib/
+endef
+
+$(eval $(call BuildPackage,gflags))
+$(eval $(call HostBuild))