Add missing #include of <openssl/mem.h>.

Change-Id: I0674f4e9b15b546237600fb2486c46aac7cb0716
Reviewed-on: https://boringssl-review.googlesource.com/28027
Reviewed-by: David Benjamin <davidben@google.com>
Commit-Queue: David Benjamin <davidben@google.com>
CQ-Verified: CQ bot account: commit-bot@chromium.org <commit-bot@chromium.org>
diff --git a/crypto/fipsmodule/ec/scalar.c b/crypto/fipsmodule/ec/scalar.c
index c1bbc6c..1bd6b02 100644
--- a/crypto/fipsmodule/ec/scalar.c
+++ b/crypto/fipsmodule/ec/scalar.c
@@ -14,6 +14,7 @@
 
 #include <openssl/ec.h>
 #include <openssl/err.h>
+#include <openssl/mem.h>
 
 #include "internal.h"
 #include "../bn/internal.h"