Makefile: Revise C compiler check

Clean up the compiler target by outsourcing the test to an own variable.
Change the print output and don't write to the build-details file.

This is in preparation for further changes.

Change-Id: I3d6f08ef030744c772b4ec0dc2c9e614fb90461d
Signed-off-by: Thomas Heijligen <thomas.heijligen@secunet.com>
Reviewed-on: https://review.coreboot.org/c/flashrom/+/58616
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Nico Huber <nico.h@gmx.de>

Makefile.d/cc_test.c

@@ -0,0 +1,6 @@
+int main(int argc, char **argv)
+{
+	(void)argc;
+	(void)argv;
+	return 0;
+}