bisect-runner.pl shouldn't generate undef warnings from internal patches

The regex wasn't handling context diffs, and two of the unified diffs were
generated with differing filenames and trailing timestamp text that it wasn't
robust against.

Author: nwc10

Porting/bisect-runner.pl

@@ -1505,7 +1505,9 @@ sub apply_patch {
     my ($patch, $what, $files) = @_;
     $what = 'patch' unless defined $what;
     unless (defined $files) {
-        $patch =~ m!^--- [ab]/(\S+)\n\+\+\+ [ba]/\1!sm;
+        # Handle context diffs (*** ---) and unified diffs (+++ ---)
+        # and ignore trailing "garbage" after the filenames
+        $patch =~ m!^[-*]{3} [ab]/(\S+)[^\n]*\n[-+]{3} [ba]/\1!sm;
         $files = " $1";
     }
     my $patch_to_use = placate_patch_prog($patch);
@@ -4411,7 +4413,7 @@ sub patch_ext {
         checkout_file('ext/DynaLoader/dl_dyld.xs', 'f556e5b971932902');
         apply_patch(<<'EOPATCH');
 diff -u a/ext/DynaLoader/dl_dyld.xs~ a/ext/DynaLoader/dl_dyld.xs
---- a/ext/DynaLoader/dl_dyld.xs~	2011-10-11 21:41:27.000000000 +0100
+--- a/ext/DynaLoader/dl_dyld.xs	2011-10-11 21:41:27.000000000 +0100
 +++ b/ext/DynaLoader/dl_dyld.xs	2011-10-11 21:42:20.000000000 +0100
 @@ -41,6 +41,35 @@
  #include "perl.h"
@@ -4462,7 +4464,7 @@ sub patch_ext {
         if ($major < 4 && !extract_from_file('util.c', qr/^form/m)) {
             apply_patch(<<'EOPATCH');
 diff -u a/ext/DynaLoader/dl_dyld.xs~ a/ext/DynaLoader/dl_dyld.xs
---- a/ext/DynaLoader/dl_dyld.xs~	2011-10-11 21:56:25.000000000 +0100
+--- a/ext/DynaLoader/dl_dyld.xs	2011-10-11 21:56:25.000000000 +0100
 +++ b/ext/DynaLoader/dl_dyld.xs	2011-10-11 22:00:00.000000000 +0100
 @@ -60,6 +60,18 @@
  #  define get_av perl_get_av