Compiling fails on CentOS 6 after this change

``` CC (gcc) [M dialog.so] dlg_cseq.o dlg_cseq.c:273: error: expected ')' before '*' token dlg_cseq.c:350: error: expected ')' before '*' token dlg_cseq.c: In function 'dlg_register_cseq_callbacks': dlg_cseq.c:538: error: 'dlg_cseq_msg_received' undeclared (first use in this function) dlg_cseq.c:538: error: (Each undeclared identifier is reported only once dlg_cseq.c:538: error: for each function it appears in.) dlg_cseq.c:539: error: 'dlg_cseq_msg_sent' undeclared (first use in this function) make[2]: *** [dlg_cseq.o] Error 1 make[1]: *** [modules] Error 1 ```