MDEV-20388 : disable inline assembly in WolfSSL if MSAN is on

A desperate attempt to workaround MemorySanitizer deficiencies.

extra/wolfssl/CMakeLists.txt

@@ -12,13 +12,16 @@ IF(MSVC)
 ELSEIF(CMAKE_SYSTEM_PROCESSOR MATCHES "x86_64")
   IF(CMAKE_C_COMPILER_ID MATCHES GNU  AND CMAKE_C_COMPILER_VERSION VERSION_LESS 4.9)
     MESSAGE_ONCE(NO_INTEL_ASSEMBLY "Disable Intel assembly for WolfSSL - compiler is too old")
+  ELSEIF(WITH_MSAN)
+    MESSAGE_ONCE(MSAN_CANT_HANDLE_IT
+      "Disable Intel assembly for WolfSSL - MSAN can't handle it")
   ELSE()
     MY_CHECK_C_COMPILER_FLAG(-maes)
     MY_CHECK_C_COMPILER_FLAG(-msse4)
     MY_CHECK_C_COMPILER_FLAG(-mpclmul)
-  ENDIF()
-  IF(have_C__maes AND have_C__msse4 AND have_C__mpclmul)
-    SET(WOLFSSL_INTELASM ON)
+    IF(have_C__maes AND have_C__msse4 AND have_C__mpclmul)
+      SET(WOLFSSL_INTELASM ON)
+    ENDIF()
   ENDIF()
 ENDIF()
 ENDIF()