ffmpeg config.log libx264 not found

gcc -D_ISOC99_SOURCE -D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE -DPIC -std=c99 -fomit-frame-pointer -fPIC -pthread -c -o /tmp/ffconf.ozEBpQNj.o /tmp/ffconf.lv9RLq0T.c
/tmp/ffconf.lv9RLq0T.c: In function 'main':
/tmp/ffconf.lv9RLq0T.c:3: warning: cast from pointer to integer of different size
gcc -Wl,--as-needed -o /tmp/ffconf.CZk4tCYn /tmp/ffconf.ozEBpQNj.o -lm -lz -pthread
check_mathfunc truncf 1
check_ld cc
check_cc
BEGIN /tmp/ffconf.lv9RLq0T.c
    1	#include <math.h>
    2	float foo(float f, float g) { return truncf(f); }
    3	int main(void){ return (int) foo; }
END /tmp/ffconf.lv9RLq0T.c
gcc -D_ISOC99_SOURCE -D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE -DPIC -std=c99 -fomit-frame-pointer -fPIC -pthread -c -o /tmp/ffconf.ozEBpQNj.o /tmp/ffconf.lv9RLq0T.c
/tmp/ffconf.lv9RLq0T.c: In function 'main':
/tmp/ffconf.lv9RLq0T.c:3: warning: cast from pointer to integer of different size
gcc -Wl,--as-needed -o /tmp/ffconf.CZk4tCYn /tmp/ffconf.ozEBpQNj.o -lm -lz -pthread
check_lib x264.h x264_encoder_encode -lx264
check_header x264.h
check_cpp
BEGIN /tmp/ffconf.lv9RLq0T.c
    1	#include <x264.h>
    2	int x;
END /tmp/ffconf.lv9RLq0T.c
gcc -D_ISOC99_SOURCE -D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE -DPIC -std=c99 -fomit-frame-pointer -fPIC -pthread -E -o /tmp/ffconf.ozEBpQNj.o /tmp/ffconf.lv9RLq0T.c
/tmp/ffconf.lv9RLq0T.c:1:18: error: x264.h: No such file or directory
ERROR: libx264 not found