Simplify malloc tool installation.

Do not build it on Windows.

From Benjamin Gilbert <bgilbert@backtick.net>.

THANKS

diff --git a/THANKS b/THANKS
index 28cfe91..e644f90 100644
--- a/THANKS
+++ b/THANKS
@@ -9,6 +9,7 @@
 Andrew Molyneux <andrew@molyneuxfamily.co.uk>
 Ankur Kothari <ankz.kothari@gmail.com>
 BALATON Zoltan <balaton@eik.bme.hu>
+Benjamin Gilbert <bgilbert@backtick.net>
 Boaz Stolk <bstolk@aweta.nl>
 Bogdan <bogiebog@gmail.com>
 Chris Nehren <cnehren+libzip@pobox.com>