[perl #49780] [config] m4 doesn't "hang", it does its job...

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# New Ticket Created by  Simon Cozens 
# Please include the string:  [perl #49780]
# in the subject line of all future correspondence about this issue. 
# <URL: http://rt.perl.org/rt3/Ticket/Display.html?id=49780 >


There's some code in config to detect 'm4 --version' "hanging" on FreeBSD. 
It doesn't hang, it just silently ignores the option and starts 
preprocessing the input from stdin.

This is true for all BSD-derived m4s - I'm actually running on *cough* 
Minix, and the same behaviour is true there.

I think this patch will DTRT, but I'm not applying it because I'd like 
someone else who's done configure stuff to have a look at it first:

Index: config/auto/m4.pm
===================================================================
--- config/auto/m4.pm   (revision 24866)
+++ config/auto/m4.pm   (working copy)
@@ -46,20 +46,11 @@

      my $has_gnu_m4;

-    # Calling 'm4 --version' hangs under FreeBSD
-    my %m4_hangs = ( freebsd => 1 );
+    # This seems to work for GNU m4 1.4.2
+    my $output = capture_output( 'echo "foo" | m4 --version' ) || '';
+    print $output, "\n" if $verbose;
+    $has_gnu_m4 = ( $output =~ m/GNU\s+[mM]4/ ) ? 1 : 0;

-    if ( $m4_hangs{$osname} ) {
-        $has_gnu_m4 = 0;
-    }
-    else {
-
-        # This seems to work for GNU m4 1.4.2
-        my $output = capture_output( 'm4', '--version' ) || '';
-        print $output, "\n" if $verbose;
-        $has_gnu_m4 = ( $output =~ m/GNU\s+[mM]4/ ) ? 1 : 0;
-    }
-
      $conf->data->set( has_gnu_m4 => $has_gnu_m4 );
      $self->set_result( $has_gnu_m4 ? 'yes' : 'no' );