Fix file-readable-p and file-executable-p in some Tramp backends

* lisp/net/tramp-archive.el (tramp-archive-handle-file-readable-p):
Use tramp-gvfs.

* lisp/net/tramp-gvfs.el (tramp-gvfs-handle-file-executable-p):
Check that FILENAME exists.
(tramp-gvfs-handle-file-readable-p): Check that FILENAME exists.
Use heuristic in case it cannot be determined correctly.
1 job for master in 49 minutes and 58 seconds (queued for 1 second)
Status Job ID Name Coverage
  Test
failed #1263
test-all

00:49:58

 
Name Stage Failure
failed
test-all Test
make[2]: *** [check-doit] Error 1
Makefile:313: recipe for target 'check-doit' failed
make[2]: Leaving directory '/builds/emacs/emacs/test'
Makefile:288: recipe for target 'check-expensive' failed
make[1]: *** [check-expensive] Error 2
make[1]: Leaving directory '/builds/emacs/emacs/test'
Makefile:962: recipe for target 'check-expensive' failed
make: *** [check-expensive] Error 2
ERROR: Job failed: exit code 1