Call va_end() before return

Fixes va_list 'arg' was opened but not closed by va_end(). (CWE-664)

core/synctex/synctex_parser_utils.c

@@ -94,6 +94,7 @@ int _synctex_log(int level, const char *prompt, const char *reason, ...)
             result = _vsnprintf(buff, buffersize - 1, reason, arg);
         }
         if (-1 == result) {
+            va_end(arg);
             // could not make the buffer big enough or simply could not write to it
             free(buff);
             return -1;
@@ -357,6 +358,7 @@ char *_synctex_merge_strings(const char *first, ...)
     do {
         size_t len = strlen(temp);
         if (UINT_MAX - len < size) {
+            va_end(arg);
             _synctex_error("!  _synctex_merge_strings: Capacity exceeded.");
             return NULL;
         }