Fix minor glitch with producing 'emacs' executable

* src/Makefile.in (LC_ALL) [!DUMPING]: Don't overwrite
previous emacs-X.Y.Z executables with new ones.
1 job for master in 56 minutes and 16 seconds (queued for 3 seconds)
Status Job ID Name Coverage
  Test
failed #564
test-all

00:56:16

 
Name Stage Failure
failed
test-all Test
make[2]: *** [check-doit] Error 1
Makefile:309: recipe for target 'check-doit' failed
make[2]: Leaving directory '/builds/emacs/emacs/test'
Makefile:284: recipe for target 'check-expensive' failed
make[1]: *** [check-expensive] Error 2
make[1]: Leaving directory '/builds/emacs/emacs/test'
Makefile:960: recipe for target 'check-expensive' failed
make: *** [check-expensive] Error 2
ERROR: Job failed: exit code 1