Make the patch -x option (only enabled with CONFIG_DEBUG) provide more information about why a patch didn't apply. (Offset of first nonmatching character at each line during seek phase.)

/* This is a separate file so libc doesn't always need regex support. */

#include <sys/types.h>
#include <regex.h>

void xregcomp(regex_t *preg, char *rexec, int cflags);