gcc-runtime: Add linux-gnuspe symlink to fix c++ headers

Some architectures can mix different TARGET_OS values, in most cases we just use one but in the ppc case, can use two different values. In this case, to use one toolchain with both, we need to ensure the symlinks exist.

This isn't ideal but does fix the ppc toolchains for the release, after which better ways of handling this can be investiaged. Without this, failures in the C++ toolchain are seen.

(From OE-Core rev: d73a2c5d3a30a6c72465b39f9a1b5217de99ee01)

index 7ce84f1..167869e 100644
@@ -53,6 +53,9 @@ do_install () {
 	if [ -d ${D}${infodir} ]; then
 		rmdir --ignore-fail-on-non-empty -p ${D}${infodir}
 	fi
+	if [ "${TARGET_OS}" = "linux-gnuspe" ]; then
+		ln -s ${TARGET_SYS} ${D}${includedir}/c++/${BINV}/${TARGET_ARCH}${TARGET_VENDOR}-linux
+	fi
 	chown -R root:root ${D}
 }