cmake: Remove use of c99 standard in plugin compilation
cmake: Remove use of c99 standard in plugin compilation

Change-Id: Iea9046e715f44604a78e4838a089bfd9766f8ef5

dfernandezlop/kms-pointerdetector,dfernandezlop/kms-pointerdetector,shelsonjava/kms-pointerdetector,Kurento/kms-pointerdetector,Kurento/kms-pointerdetector,shelsonjava/kms-pointerdetector,dfernandezlop/kms-pointerdetector,Kurento/kms-pointerdetector,shelsonjava/kms-pointerdetector