I found if remove first '\n' from the *str,then run emacs will not hang.*
*May be it has nothing to do with font-lock, just str parsing ?*

(let ((str "#define SLOGE(...)\n
((void)__android_log_buf_print(LOG_ID_SYSTEM, ANDROID_LOG_ERROR, LOG_TAG,\n

change to
(let ((str "#define SLOGE(...)
((void)__android_log_buf_print(LOG_ID_SYSTEM, ANDROID_LOG_ERROR, LOG_TAG,\n