librhash: Implement bswap_32 as a function even in strict C90 mode

We cannot fall back to the macro implementation because some call sites
may call it with an argument like `*ptr++` that has side effects.

Utilities/cmlibrhash/librhash/byte_order.h

@@ -103,15 +103,12 @@ static inline uint32_t bswap_32(uint32_t x) {
 # define bswap_32(x) __builtin_bswap32(x)
 #elif (_MSC_VER > 1300) && (defined(CPU_IA32) || defined(CPU_X64)) /* MS VC */
 # define bswap_32(x) _byteswap_ulong((unsigned long)x)
-#elif !defined(__STRICT_ANSI__)
+#else
 /* general bswap_32 definition */
-static inline uint32_t bswap_32(uint32_t x) {
+static uint32_t bswap_32(uint32_t x) {
 	x = ((x << 8) & 0xFF00FF00) | ((x >> 8) & 0x00FF00FF);
 	return (x >> 16) | (x << 16);
 }
-#else
-#define bswap_32(x) ((((x) & 0xff000000) >> 24) | (((x) & 0x00ff0000) >>  8) | \
-	(((x) & 0x0000ff00) <<  8) | (((x) & 0x000000ff) << 24))
 #endif /* bswap_32 */
 
 #if defined(__GNUC__) && (__GNUC__ >= 4) && (__GNUC__ > 4 || __GNUC_MINOR__ >= 3)