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/location.h

@@ -73,8 +73,8 @@ static inline bool
 equal_boundaries (boundary a, boundary b)
 {
   return (a.column == b.column
-	  && a.line == b.line
-	  && UNIQSTR_EQ (a.file, b.file));
+          && a.line == b.line
+          && UNIQSTR_EQ (a.file, b.file));
 }
 
 /* A location, that is, a region of source code.  */
@@ -96,7 +96,7 @@ extern location const empty_location;
 /* Set *LOC and adjust scanner cursor to account for token TOKEN of
    size SIZE.  */
 void location_compute (location *loc,
-		       boundary *cur, char const *token, size_t size);
+                       boundary *cur, char const *token, size_t size);
 
 /* Print location to file. Return number of actually printed
    characters.  */