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.

lib/bitsetv.c

@@ -27,7 +27,7 @@
    type TYPE.  */
 bitset *
 bitsetv_alloc (bitset_bindex n_vecs, bitset_bindex n_bits,
-	       enum bitset_type type)
+               enum bitset_type type)
 {
   size_t vector_bytes;
   size_t bytes;
@@ -116,7 +116,7 @@ bitsetv_transitive_closure (bitsetv bsetv)
   for (i = 0; bsetv[i]; i++)
     for (j = 0; bsetv[j]; j++)
       if (bitset_test (bsetv[j], i))
-	bitset_or (bsetv[j], bsetv[j], bsetv[i]);
+        bitset_or (bsetv[j], bsetv[j], bsetv[i]);
 }
 
 
@@ -139,7 +139,7 @@ bitsetv_reflexive_transitive_closure (bitsetv bsetv)
    FILE.  */
 void
 bitsetv_dump (FILE *file, char const *title, char const *subtitle,
-	      bitsetv bsetv)
+              bitsetv bsetv)
 {
   bitset_windex i;