build: add a config option for choosing the prefered standard c++ library and add uclibc++.mk to make this easy to handle in packages

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@32369 3c298f89-4303-0410-b956-a3cf2f4a3e73

Author: nbd

Config.in

@@ -395,6 +395,21 @@ menu "Global build settings"
 		  Note that this will make the system libraries incompatible with most of the packages
 		  that are not selected during the build process
 
+	choice
+		prompt "Preferred standard C++ library"
+		default USE_LIBSTDCXX if USE_EGLIBC
+		default USE_UCLIBCXX
+		help
+		  Select the preferred standard C++ library for all packages that support this.
+
+		config USE_UCLIBCXX
+			bool "uClibc++"
+
+		config USE_LIBSTDCXX
+			bool "libstdc++"
+
+	endchoice
+
 endmenu
 
 menuconfig DEVEL

include/package.mk

@@ -5,6 +5,8 @@
 # See /LICENSE for more information.
 #
 
+__package_mk:=1
+
 all: $(if $(DUMP),dumpinfo,compile)
 
 PKG_BUILD_DIR ?= $(BUILD_DIR)/$(PKG_NAME)$(if $(PKG_VERSION),-$(PKG_VERSION))

include/uclibc++.mk

@@ -0,0 +1,12 @@
+ifndef DUMP
+  ifdef __package_mk
+    $(error uclibc++.mk must be included before package.mk)
+  endif
+endif
+
+PKG_PREPARED_DEPENDS += CONFIG_USE_UCLIBCXX
+CXX_DEPENDS = +USE_UCLIBCXX:uclibcxx +USE_LIBSTDCXX:libstdcpp
+
+ifneq ($(CONFIG_USE_UCLIBCXX),)
+  TARGET_CXX="g++-uc"
+endif