Small cleanups

Change-Id: Ib66507b8934bc8019a762d24d5311411e044ec84
diff --git a/native/jni/src/char_utils.cpp b/native/jni/src/char_utils.cpp
index 223291f..9d886da31 100644
--- a/native/jni/src/char_utils.cpp
+++ b/native/jni/src/char_utils.cpp
@@ -889,7 +889,7 @@
             - static_cast<int>((static_cast<const struct LatinCapitalSmallPair *>(b))->capital);
 }
 
-unsigned short latin_tolower(unsigned short c) {
+unsigned short latin_tolower(const unsigned short c) {
     struct LatinCapitalSmallPair *p =
             static_cast<struct LatinCapitalSmallPair *>(bsearch(&c, SORTED_CHAR_MAP,
                     sizeof(SORTED_CHAR_MAP) / sizeof(SORTED_CHAR_MAP[0]),