Implement & link m_mail_check[_ovl].c

rel/m_mail_check.c

@@ -0,0 +1,7 @@
+#include "m_mail_check.h"
+
+#include "m_mail_check_ovl.h"
+
+extern int mMC_get_mail_hit_rate(int* len, u8* str) {
+  return mMck_check_key_hit(len, str);
+}