`make tags` fixes (GH-717)

* Fix `make tags` warnings

`make tags` target tries to find C sources and headers in "Grammar" and
"Mac" folders and generates these warnings:

    ctags: Warning: cannot open source file "Grammar/*.[ch]" : No such file or directory
    ctags: Warning: cannot open source file "Mac/*.[ch]" : No such file or directory

This commit changes $SRCDIRS variable in configure.ac to remote these
directories. This variable is used only for tags generation.

Also, "configure" was regenerated with `autoreconf`.

* Fix `make tags` fail on non-default tag names

When ctags overrides default tags filename (e.g. `-f .tags`) `make tags`
is failed because it assumes to see default `tags` filename:

    sort: cannot read: tags: No such file or directory

This commit explicitly specifies "tags" filename for tags generation.

Makefile.pre.in

@@ -1555,7 +1555,7 @@ autoconf:
 tags::
 	cd $(srcdir); \
 	ctags -w Include/*.h; \
-	for i in $(SRCDIRS); do ctags -w -a $$i/*.[ch]; \
+	for i in $(SRCDIRS); do ctags -f tags -w -a $$i/*.[ch]; \
 	done; \
 	LC_ALL=C sort -o tags tags
 

configure

@@ -16320,7 +16320,7 @@ do
 done
 
 
-SRCDIRS="Parser Grammar Objects Python Modules Mac Programs"
+SRCDIRS="Parser Objects Python Modules Programs"
 { $as_echo "$as_me:${as_lineno-$LINENO}: checking for build directories" >&5
 $as_echo_n "checking for build directories... " >&6; }
 for dir in $SRCDIRS; do

configure.ac

@@ -5200,7 +5200,7 @@ do
 done
 
 AC_SUBST(SRCDIRS)
-SRCDIRS="Parser Grammar Objects Python Modules Mac Programs"
+SRCDIRS="Parser Objects Python Modules Programs"
 AC_MSG_CHECKING(for build directories)
 for dir in $SRCDIRS; do
     if test ! -d $dir; then