Improve windows-abandoning in makefile

Change-Id: I8d004e5e35651dd4db5319d451b290acbaa4d874
diff --git a/Makefile.PL b/Makefile.PL
index 5bbbf66..03fd375 100644
--- a/Makefile.PL
+++ b/Makefile.PL
@@ -4,7 +4,7 @@
 
 use ExtUtils::MakeMaker;
 
-if ($^O =~ /^(MSWin32|cygwin)$/i) {
+if ($^O =~ /^(MSWin32|cygwin|msys)$/i) {
   die "No support for Windows.\n";
 };