gcc: drop libstdc++ patch (#445308)

## 1. Patches relevant on every platform ####################################

[ ]

# Pass the path to a C++ compiler directly in the Makefile.in

++ optional (!lib.systems.equals targetPlatform hostPlatform) ./libstdc++-target.patch

++ optionals noSysDirs (

optionals noSysDirs (

  [

    # Do not try looking for binaries and libraries in /lib and /usr/lib

    ./gcc-12-no-sys-dirs.patch

Patch to make the target libraries 'configure' scripts find the proper CPP.

I noticed that building the mingw32 cross compiler.

Looking at the build script for mingw in archlinux, I think that only nixos

needs this patch. I don't know why.

diff --git a/Makefile.in b/Makefile.in

index 93f66b6..d691917 100644

--- a/Makefile.in

+++ b/Makefile.in

@@ -266,6 +266,7 @@ BASE_TARGET_EXPORTS = \

 	AR="$(AR_FOR_TARGET)"; export AR; \

 	AS="$(COMPILER_AS_FOR_TARGET)"; export AS; \

 	CC="$(CC_FOR_TARGET) $(XGCC_FLAGS_FOR_TARGET) $$TFLAGS"; export CC; \

+	CPP="$(CC_FOR_TARGET) $(XGCC_FLAGS_FOR_TARGET) $$TFLAGS -E"; export CC; \

 	CFLAGS="$(CFLAGS_FOR_TARGET)"; export CFLAGS; \

 	CONFIG_SHELL="$(SHELL)"; export CONFIG_SHELL; \

 	CPPFLAGS="$(CPPFLAGS_FOR_TARGET)"; export CPPFLAGS; \

@@ -291,11 +292,13 @@ BASE_TARGET_EXPORTS = \

 RAW_CXX_TARGET_EXPORTS = \

 	$(BASE_TARGET_EXPORTS) \

 	CXX_FOR_TARGET="$(RAW_CXX_FOR_TARGET)"; export CXX_FOR_TARGET; \

-	CXX="$(RAW_CXX_FOR_TARGET) $(XGCC_FLAGS_FOR_TARGET) $$TFLAGS"; export CXX;

+	CXX="$(RAW_CXX_FOR_TARGET) $(XGCC_FLAGS_FOR_TARGET) $$TFLAGS"; export CXX; \

+	CXXCPP="$(RAW_CXX_FOR_TARGET) $(XGCC_FLAGS_FOR_TARGET) $$TFLAGS -E"; export CXX;

 NORMAL_TARGET_EXPORTS = \

 	$(BASE_TARGET_EXPORTS) \

-	CXX="$(CXX_FOR_TARGET) $(XGCC_FLAGS_FOR_TARGET) $$TFLAGS"; export CXX;

+	CXX="$(CXX_FOR_TARGET) $(XGCC_FLAGS_FOR_TARGET) $$TFLAGS"; export CXX; \

+	CXXCPP="$(CXX_FOR_TARGET) $(XGCC_FLAGS_FOR_TARGET) $$TFLAGS -E"; export CXX;

 # Where to find GMP

 HOST_GMPLIBS = @gmplibs@