give Win32 miniperl a real getcwd for build perf

getcwd() is now 605x faster for Win32 miniperl.
------------------------------
use Cwd;
Cwd::getcwd() for(0..10000);
------------------------------
before
C:\p523\src\win32>timeit -f t.dat ..\miniperl -I..\lib t.pl
Version Number:   Windows NT 6.1 (Build 7601)
Exit Time:        2:03 am, Thursday, December 10 2015
Elapsed Time:     0:01:12.438
Process Time:     0:00:14.289
System Calls:     5802378
Context Switches: 1455066
Page Faults:      5250724
Bytes Read:       76809789
Bytes Written:    5278717
Bytes Other:      10407004
after
C:\p523\src\win32>timeit -f t.dat ..\miniperl -I..\lib t.pl
Version Number:   Windows NT 6.1 (Build 7601)
Exit Time:        1:20 am, Thursday, December 10 2015
Elapsed Time:     0:00:00.119
Process Time:     0:00:00.124
System Calls:     4658
Context Switches: 540
Page Faults:      1127
Bytes Read:       99074
Bytes Written:    0
Bytes Other:      12888

1 files changed, 9 insertions, 0 deletions

diff --git a/cpan/ExtUtils-MakeMaker/t/lib/MakeMaker/Test/NoXS.pm b/cpan/ExtUtils-MakeMaker/t/lib/MakeMaker/Test/NoXS.pm
index 45faf7e230..df36e82c21 100644
--- a/cpan/ExtUtils-MakeMaker/t/lib/MakeMaker/Test/NoXS.pm
+++ b/cpan/ExtUtils-MakeMaker/t/lib/MakeMaker/Test/NoXS.pm
@@ -10,6 +10,15 @@ require XSLoader;
 # Things like Cwd key on this to decide if they're running miniperl
 delete $DynaLoader::{boot_DynaLoader};
 
+if ($^O eq 'MSWin32') {
+    require Win32;
+    my $GetCwd = *{'Win32::GetCwd'}{CODE};
+    my $SetChildShowWindow = *{'Win32::SetChildShowWindow'}{CODE};
+    %{*main::Win32::{HASH}} = ();
+    *{'Win32::GetCwd'} = $GetCwd;
+    *{'Win32::SetChildShowWindow'} = $SetChildShowWindow;
+}
+
 # This isn't 100%.  Things like Win32.pm will crap out rather than
 # just not load.  See ExtUtils::MM->_is_win95 for an example
 no warnings 'redefine';