Pacify GCC -Wmaybe-uninitialized

* src/dired.c (directory_files_internal):
Pacify GCC 7.4.0-1ubuntu1~18.04.1 x86-64.
1 job for master in 79 minutes and 8 seconds (queued for 1 second)
Status Job ID Name Coverage
  Test
failed #3329
test-all

01:19:08

 
Name Stage Failure
failed
test-all Test
Makefile:319: recipe for target 'check-doit' failed
make[2]: *** [check-doit] Error 1
make[2]: Leaving directory '/builds/emacs/emacs/test'
make[1]: *** [check-expensive] Error 2
Makefile:294: recipe for target 'check-expensive' failed
make[1]: Leaving directory '/builds/emacs/emacs/test'
make: *** [check-expensive] Error 2
Makefile:959: recipe for target 'check-expensive' failed
ERROR: Job failed: exit code 1