Skip .#* temporaries when finding sources

Skip .#* temporaries when finding sources

Without this patch, ‘make check’ can fail with the diagnostic
‘invalid syntax in conditional’ if there is an Emacs temporary
file whose name starts with ‘.#’, because the ‘#’ is treated as
the start of a Make comment.
* lisp/Makefile.in (loaddefs, tagsfiles, check-defun-deps):
* test/Makefile.in (ELFILES):
Skip files starting with ‘.’, so that the .#* files do not cause
trouble.  (We cannot easily skip just files starting with ‘.#’,
since ‘#’ starts a Make comment!)