Cleanup: strcmp/strncmp -> STREQ/STREQLEN (in boolean usage).

Makes usage of those funcs much more clear, we even had mixed '!strcmp(foo, bar)'
and 'strcmp(foo, bar) == 0' in several places...

source/blender/python/intern/bpy_app_translations.c

@@ -260,7 +260,7 @@ const char *BPY_app_translations_py_pgettext(const char *msgctxt, const char *ms
 		return msgid;
 
 	tmp = BLF_lang_get();
-	if (strcmp(tmp, locale) || !_translations_cache) {
+	if (!STREQ(tmp, locale) || !_translations_cache) {
 		PyGILState_STATE _py_state;
 
 		BLI_strncpy(locale, tmp, STATIC_LOCALE_SIZE);