toolchain: Replace GCC_VERSION, CLANG_VERSION and BUILD_ASSERT macros

GCC_VERSION is defined in a few modules, and those headers are often
included first, so replace the one used in zephyr with
TOOLCHAIN_GCC_VERSION. Do the same with CLANG_VERSION, replacing it with
TOOLCHAIN_CLANG_VERSION.

BUILD_ASSERT is also defined in include/toolchain/common.h, which might
get included before gcc.h. We want to use the gcc-specific one instead
of the general one.

Signed-off-by: Keith Packard <[email protected]>
(cherry picked from commit c58c76e)

include/toolchain/gcc.h

@@ -48,8 +48,9 @@
 #endif
 
 
+#undef BUILD_ASSERT /* clear out common version */
 /* C++11 has static_assert built in */
-#ifdef __cplusplus
+#if defined(__cplusplus) && (__cplusplus >= 201103L)
 #define BUILD_ASSERT(EXPR, MSG...) static_assert(EXPR, "" MSG)
 
 /*