Changes to allow compilation of MathFunctions.c

BUG=none
TEST=compilation succeeds:
   cc -Wall -Werror -c -o /dev/null MathFunctions.c

Change-Id: I8605ee2d66c2999fee201add9d1312725c8c9d00
Signed-off-by: Vadim Bendebury <vbendeb@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/274240
Reviewed-by: Utkarsh Sanghi <usanghi@chromium.org>
diff --git a/MathFunctions.c b/MathFunctions.c
index 04a0969..5b52617 100644
--- a/MathFunctions.c
+++ b/MathFunctions.c
@@ -5,6 +5,8 @@
 // Level 00 Revision 01.16
 // October 30, 2014
 
+#include <string.h>
+
 #include "OsslCryptoEngine.h"
 //
 //