bisect-runner.pl now runs the testcase for targets config.{sh,h}

Previously for these two targets it assumed --test-build if a --match
wasn't supplied, and never ran a test case if one was supplied. Now
--test-build must be specified explicitly, otherwise the test case will be
run. For example, this makes it easy to bisect using a testcase which greps
config.sh or config.h. (Of course, one can do roughly this with the --match
option, but this will match against all generated files, which may generate
false positives.)

Porting/bisect-runner.pl

@@ -1071,7 +1071,11 @@ sub match_and_exit {
 
 if ($target =~ /config\.s?h/) {
     match_and_exit($target) if $match && -f $target;
-    report_and_exit(!-f $target, 'could build', 'could not build', $target);
+    report_and_exit(!-f $target, 'could build', 'could not build', $target)
+        if $options{'test-build'};
+
+    my $ret = system @ARGV;
+    report_and_exit($ret, 'zero exit from', 'non-zero exit from', "@ARGV");
 } elsif (!-f 'config.sh') {
     # Skip if something went wrong with Configure