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 <frank.vibrans@amd.com>

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This patch is compressed to retain Linux line endings.