regex: avoid glibc deadlock during configure glibc has a known bug where certain corruptions of the heap can cause malloc to default to printing a debug message that includes a backtrace, but the act of getting the backtrace uses dlopen which in turn calls into malloc, causing a recursive lock ending in deadlock. Thus, when configure is probing for a known glibc heap corruption bug, the overall configure would hang. The solution suggested by glibc developers is to force malloc to quit printing debug messages, which avoids recursive malloc. * m4/regex.m4 (gl_REGEX): Avoid recursive malloc deadlock when glibc bug 15078 in turn triggers bug 16159. Reported by Michal Privoznik. Signed-off-by: Eric Blake <eblake@redhat.com>

#include <config.h>

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

/* A trivial substitute for 'fchown'.

   DJGPP 2.03 and earlier (and perhaps later) don't have 'fchown',
   so we pretend no-one has permission for this operation. */

int
fchown (int fd, uid_t uid, gid_t gid)
{
  errno = EPERM;
  return -1;
}