complier.h: add __always_inline and use it in code base

Add a __always_inline macro that wraps __attribute__((always_inline))
and replace current users with the macro, excluding files under
src/vendorcode.

Change-Id: Ic57e474c1d2ca7cc0405ac677869f78a28d3e529
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: https://review.coreboot.org/28587
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Julius Werner <jwerner@google.com>

src/commonlib/lz4_wrapper.c

@@ -84,7 +84,7 @@ typedef uint32_t U32;
 typedef  int32_t S32;
 typedef uint64_t U64;
 
-#define FORCE_INLINE static inline __attribute__((always_inline))
+#define FORCE_INLINE static __always_inline
 #define likely(expr) __builtin_expect((expr) != 0, 1)
 #define unlikely(expr) __builtin_expect((expr) != 0, 0)