[coreboot] A patch to remove AMD Agesa requirement for standard include files

[Vibrans, Frank]

Remove AMD Agesa requirement for standard include files

This change modifies Makefile.inc to add the -nostdinc flag to the default
CFLAGS value and removes the test for non-AMD Agesa builds.  Other code is
added to the gcc-intrin.h file in the Agesa Include folder to make the
requirement for the standard includes obsolete from the Agesa perspective.

Signed-off by Frank Vibrans

This patch is compressed to retain Linux line endings.