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.

etc/bench.pl.in

@@ -284,8 +284,8 @@ for my $size (1 .. $max)
   {
     use Text::Wrap;
     print $out wrap ("| ", "   ",
-		     (map { "\"$_\"" } (1 .. $size)),
-		     " END \n"),
+                     (map { "\"$_\"" } (1 .. $size)),
+                     " END \n"),
                "    { \$\$ = $size; }\n";
   };
 print $out ";\n";
@@ -411,7 +411,7 @@ static int yylex (void);
 %token <ival> NUM "number"
 %type  <ival> exp
 
-%nonassoc '=' /* comparison	       */
+%nonassoc '=' /* comparison            */
 %left '-' '+'
 %left '*' '/'
 %left NEG     /* negation--unary minus */
@@ -640,13 +640,13 @@ EOF
 
 %%
 result:
-  text			{ /* Throw away the result. */ }
+  text                  { /* Throw away the result. */ }
 ;
 
 text:
-  /* nothing */		{ /* This will generate an empty string */ }
-| text TEXT		{ std::swap ($$, $2); }
-| text NUMBER		{ $$ = string_cast($2); }
+  /* nothing */         { /* This will generate an empty string */ }
+| text TEXT             { std::swap ($$, $2); }
+| text NUMBER           { $$ = string_cast($2); }
 ;
 EOF
     }
@@ -663,13 +663,13 @@ EOF
 
 %%
 result:
-  text			{ delete $1; }
+  text                  { delete $1; }
 ;
 
 text:
-  /* nothing */		{ $$ = new std::string; }
-| text TEXT		{ delete $1; $$ = $2; }
-| text NUMBER		{ delete $1; $$ = new std::string (string_cast ($2)); }
+  /* nothing */         { $$ = new std::string; }
+| text TEXT             { delete $1; $$ = $2; }
+| text NUMBER           { delete $1; $$ = new std::string (string_cast ($2)); }
 ;
 EOF
     }