kbuild: dummy-tools: support MPROFILE_KERNEL checks for ppc

ppc64le checks for -mprofile-kernel to define MPROFILE_KERNEL Kconfig.
Kconfig calls arch/powerpc/tools/gcc-check-mprofile-kernel.sh for that
purpose. This script performs two checks:
1) build with -mprofile-kernel should contain "_mcount"
2) build with -mprofile-kernel with a function marked as "notrace"
   should not produce "_mcount"

So support this in dummy-tools' gcc, so that we have MPROFILE_KERNEL
always true.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

scripts/dummy-tools/gcc

@@ -73,6 +73,15 @@ if arg_contain -S "$@"; then
 		echo "%gs"
 		exit 0
 	fi
+
+	# For arch/powerpc/tools/gcc-check-mprofile-kernel.sh
+	if arg_contain -m64 "$@" && arg_contain -mlittle-endian "$@" &&
+		arg_contain -mprofile-kernel "$@"; then
+		if ! test -t 0 && ! grep -q notrace; then
+			echo "_mcount"
+		fi
+		exit 0
+	fi
 fi
 
 # To set GCC_PLUGINS