src/h264.c: include utils.h for request_log() prototype

GCC's -Wimplicit-function-declaration is fatal in current toolchains
(GCC 14+) but was a warning when this code was written. h264.c uses
request_log() in two places without including utils.h; the build was
quietly relying on an implicit declaration that recent compilers reject.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/h264.c

@@ -36,6 +36,7 @@
 #include <h264-ctrls.h>
 
 #include "request.h"
+#include "utils.h"
 #include "surface.h"
 #include "v4l2.h"