toolchain: separate c++ compiler from libstdc++ presence

We may want a c++ compiler, but no libstdc++ on the system. For example,
firmware that isn't linked with the system libstdc++. These packages can
depend on BR2_CPP instead of BR2_INSTALL_LIBSTDCPP.

Signed-off-by: Jeremy Kerr <[email protected]>

Author: jk-ozlabs

package/Makefile.in

@@ -361,7 +361,7 @@ else
 DISABLE_IPV6= --disable-ipv6
 endif
 
-ifneq ($(BR2_INSTALL_LIBSTDCPP),y)
+ifneq ($(BR2_CPP),y)
 TARGET_CONFIGURE_OPTS+=CXX=false
 endif
 

package/gcc/Config.in.host

@@ -126,13 +126,21 @@ config BR2_EXTRA_GCC_CONFIG_OPTIONS
 	  initial, gcc intermediate and gcc final passes.
 
 config BR2_TOOLCHAIN_BUILDROOT_CXX
-	bool "Enable C++ support"
-	select BR2_INSTALL_LIBSTDCPP
+	bool "Enable C++ compiler support"
+	select BR2_CPP
 	depends on !(BR2_GCC_VERSION_4_2_2_AVR32_2_1_5 && \
 		     BR2_TOOLCHAIN_BUILDROOT_LOCALE)
 	help
 	  Enable this option if you want your toolchain to support the
-	  C++ language and you want C++ libraries to be installed on
+	  C++ language.
+
+config BR2_TOOLCHAIN_BUILDROOT_LIBSTDCPP
+	bool "Install C++ libraries"
+	default y
+	select BR2_INSTALL_LIBSTDCPP
+	depends on BR2_TOOLCHAIN_BUILDROOT_CXX
+	help
+	  Enable this option if you want C++ libraries to be installed on
 	  your target system.
 
 comment "C++ support broken in uClibc with locale enabled with gcc 4.2"

package/gcc/gcc-final/gcc-final.mk

@@ -43,7 +43,7 @@ endef
 
 # Languages supported by the cross-compiler
 GCC_FINAL_CROSS_LANGUAGES-y = c
-GCC_FINAL_CROSS_LANGUAGES-$(BR2_INSTALL_LIBSTDCPP) += c++
+GCC_FINAL_CROSS_LANGUAGES-$(BR2_CPP) += c++
 GCC_FINAL_CROSS_LANGUAGES-$(BR2_INSTALL_FORTRAN) += fortran
 GCC_FINAL_CROSS_LANGUAGES-$(BR2_INSTALL_OBJC)    += objc
 GCC_FINAL_CROSS_LANGUAGES = $(subst $(space),$(comma),$(GCC_FINAL_CROSS_LANGUAGES-y))

toolchain/toolchain-common.in

@@ -26,8 +26,12 @@ config BR2_USE_WCHAR
 config BR2_ENABLE_LOCALE
 	bool
 
+config BR2_CPP
+	bool
+
 config BR2_INSTALL_LIBSTDCPP
 	bool
+	select BR2_CPP
 
 config BR2_TOOLCHAIN_HAS_THREADS
 	bool