global: remove unnecessary horizontal tabs.

This change was made by applying emacs' untabify function to
nearly all files in Bison's repository.  Required tabs in make
files, ChangeLog, regexps, and test code were manually skipped.
Other notable exceptions and changes are listed below.
* bootstrap: Skip because we sync this with gnulib.
* data/m4sugar/foreach.m4
* data/m4sugar/m4sugar.m4: Skip because we sync these with
Autoconf.
* djgpp: Skip because I don't know how to test djgpp properly, and
this code appears to be unmaintained anyway.
* README-hacking (Hacking): Specify that tabs should be avoided
where not required.

src/gram.h

@@ -105,8 +105,8 @@
 # include "location.h"
 # include "symtab.h"
 
-# define ISTOKEN(i)	((i) < ntokens)
-# define ISVAR(i)	((i) >= ntokens)
+# define ISTOKEN(i)     ((i) < ntokens)
+# define ISVAR(i)       ((i) >= ntokens)
 
 extern int nsyms;
 extern int ntokens;
@@ -254,7 +254,7 @@ size_t ritem_longest_rhs (void);
 
 /* Print the grammar's rules that match FILTER on OUT under TITLE.  */
 void grammar_rules_partial_print (FILE *out, const char *title,
-				  rule_filter filter);
+                                  rule_filter filter);
 
 /* Print the grammar's useful rules on OUT.  */
 void grammar_rules_print (FILE *out);