$ grep 264 config.log 
configure:26483: checking for x264_encoder_open in -lx264
configure:26518: gcc -o conftest -g -O2   conftest.c -lx264 -lpthread -lm  -lm -ldl -lpthread >&5
configure:26625: checking x264.h usability
configure:26666: checking x264.h presence
/usr/include/x264.h:32:4: warning: #warning You must include stdint.h or inttypes.h before x264.h
configure:26729: checking for x264.h
ac_cv_header_x264_h=yes
ac_cv_lib_x264_x264_encoder_open=yes
LIBX264_LIBS='-lx264'