MT#55283 slightly improved STR_DUP

This should give slightly better performance due to not having to look
for the terminator byte twice. Not benchmarked. No-op.

Change-Id: I458a06b492393fcf5b186a61b69acabdf63a216e

lib/str.h

@@ -41,7 +41,11 @@ TYPED_GQUEUE(str, str)
 #define STR_GS(s) ((str) { (s)->str, (s)->len })
 #define STR_LEN(s, len) ((str) { (char *) (s), len })
 #define STR_LEN_ASSERT(s, len) ({ assert(sizeof(s) >= len); (str) { (char *) (s), len }; })
+#if GLIB_CHECK_VERSION(2,68,0)
+#define STR_DUP(s) ({ size_t __l = strlen(s); (str) { g_memdup2(s, __l + 1), __l }; })
+#else
 #define STR_DUP(s) ((str) { g_strdup(s), strlen(s) })
+#endif
 #define STR_CONST_BUF(buf) ((str) { (char *) &buf, sizeof(buf) })