Get stdint.h in sync between ARMv7 and x86

- add s8, s16, s32 types to x86

Change-Id: Ib9c260fc4f72029492f2d935dbb822cc3ff83cc4
Signed-off-by: Stefan Reinauer <reinauer@google.com>
Reviewed-on: http://review.coreboot.org/2050
Tested-by: build bot (Jenkins)
Reviewed-by: David Hendricks <dhendrix@chromium.org>

src/arch/x86/include/stdint.h

@@ -71,6 +71,10 @@ typedef uint32_t u32;
 #if __HAVE_LONG_LONG__
 typedef uint64_t u64;
 #endif
+typedef int8_t s8;
+typedef int16_t s16;
+typedef int32_t s32;
+
 
 #undef __HAVE_LONG_LONG__