Fix more clang-tidy warnings.

Changes imported from Chih-hung Hsieh's CL at
https://android-review.googlesource.com/c/235696/.

Change-Id: I02f170f0a059c21a8d6f221dcc779f6476f36bbf
Reviewed-on: https://boringssl-review.googlesource.com/12026
Reviewed-by: Steven Valdez <svaldez@google.com>
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/include/openssl/bn.h b/include/openssl/bn.h
index 66945cb..01f75ec 100644
--- a/include/openssl/bn.h
+++ b/include/openssl/bn.h
@@ -582,7 +582,7 @@
 /* Random and prime number generation. */
 
 /* The following are values for the |top| parameter of |BN_rand|. */
-#define BN_RAND_TOP_ANY    -1
+#define BN_RAND_TOP_ANY    (-1)
 #define BN_RAND_TOP_ONE     0
 #define BN_RAND_TOP_TWO     1