$ cat foo.c
#include <php_main.h>
int main(void) { 
  return 0; 
}
$ /usr/bin/gcc foo.c -I/usr/local/include -I/usr/local/include/php -I/usr/local/include/php/main -I/usr/local/include/php/TSRM -I/usr/local/include/php/Zend -I/usr/local/include/php/ext -I/usr/local/include/php/ext/date/lib -o foo