Hello,

while rebasing the gzip in fedora I've encountered the build failure from
the $SUBJ.
A bit more info:
- happens only when configured with the --enable-dfltcc
- introduced  by the [1] (the "errno" variable doesn't seem to be used
outside of the scope of the patch)
- build completes when the "--enable-dfltcc" is not used or when the [1] is
reversed
- The actual error (I can provide patch if needed):

dfltcc.c:441:15: error: 'errno' undeclared (first use in this function)
  441 |               errno = 0;
      |               ^~~~~
dfltcc.c:28:1: note: 'errno' is defined in header '<errno.h>'; this is
probably fixable by adding '#include <errno.h>'
   27 | #include "gzip.h"
  +++ |+#include <errno.h>
   28 |
dfltcc.c:441:15: note: each undeclared identifier is reported only
once for each function it appears in
  441 |               errno = 0;
      |               ^~~~~
make[2]: *** [Makefile:2050: dfltcc.o] Error 1




[1]:
https://cgit.git.savannah.gnu.org/cgit/gzip.git/commit/?h=v1.14&id=23ddd95f3e152423fe0dfc96ff31d4130a65e8cf