Fix __attribute__ for new formals

Signed-off-by: Anna Rift <[email protected]>

runtime/include/chpllaunch.h

@@ -47,7 +47,7 @@ void chpl_append_to_largv(int* largc, const char*** largv, int* largv_len,
                           const char* arg);
 void chpl_append_to_cmd(char** cmdBufPtr, int* charsWritten,
                         const char* format, ...)
-  __attribute__((format(printf, 2, 3)));
+  __attribute__((format(printf, 3, 4)));
 int chpl_run_utility1K(const char *command, char *const argv[],
                        char *outbuf, int outbuflen);
 int chpl_run_cmdstr(const char *commandStr, char *outbuf, int outbuflen);