Replace non-standard memory.h with cstring (fixes #3665)

cef_string_wrappers.h uses a non-standard header memory.h, which breaks
the build on UCRT environments. Replace <memory.h> include with <cstring>,
which is guaranteed to contain strlen.

include/internal/cef_string_wrappers.h

@@ -31,7 +31,7 @@
 #define CEF_INCLUDE_INTERNAL_CEF_STRING_WRAPPERS_H_
 #pragma once
 
-#include <memory.h>
+#include <cstring>
 #include <string>
 
 #include "include/internal/cef_string_types.h"