Remove a trailing space

Author: atetubou

libcxx/include/string.h

@@ -64,7 +64,7 @@ size_t strlen(const char* s);
 #    include_next <string.h>
 #  endif
 
-#  include <stddef.h> 
+#  include <stddef.h>
 
 // MSVCRT, GNU libc and its derivates may already have the correct prototype in
 // <string.h>. This macro can be defined by users if their C library provides