Make it easier to debug configure test failures.
--- a/Makefile.PL
+++ b/Makefile.PL
@@ -13,7 +13,7 @@ for (@ARGV) {
 
 my @libs;
 
-my $ac = Config::AutoConf->new;
+my $ac = Config::AutoConf->new(logfile => "config.log");
 
 if (defined(my $ccflags = $args{CCFLAGS})) {
     $ac->check_compiler_flags($ccflags);