Adds crypto-mdebug as a valid option

Adds crypto-mdebug as a valid option. Fixes https://github.com/openssl/openssl/issues/537

Signed-off-by: Rich Salz <rsalz@openssl.org>
Reviewed-by: Tim Hudson <tjh@openssl.org>

Configure

diff --git a/Configure b/Configure
index c6c68bf..3a5bd8e 100755
--- a/Configure
+++ b/Configure
@@ -834,6 +834,7 @@
     "cmac",
     "cms",
     "comp",
+    "crypto-mdebug",
     "ct",
     "deprecated",
     "des",