Update JNI code in preparation for ICU 59 switching to C++11 char16_t.

ICU 59 (update pending on the aosp/icu59 branch) has switched to using
the C++11 char16_t data type, which is a distinct type from uint16_t
(which is what JNI's jchar is typedef'd as), even though they are
bitwise identical.

All code that passes UTF-16 data between ICU4C and JNI must therefore be
updated with typecasts in the appropriate places before ICU 59 is merged
to aosp/master.

Bug: 37554848
Test: make
Change-Id: Ibbc90d2b603382d4715551d05c4a6a462529542d
Merged-In: Ic84a94be82acbef41f80cc113d5da485ce54ae29

core/jni/android_text_AndroidBidi.cpp

@@ -42,7 +42,7 @@ static jint runBidi(JNIEnv* env, jobject obj, jint dir, jcharArray chsArray,
             // Set callbacks to override bidi classes of new emoji
             ubidi_setClassCallback(
                     bidi, minikin::emojiBidiOverride, nullptr, nullptr, nullptr, &status);
-            ubidi_setPara(bidi, chs, n, dir, NULL, &status);
+            ubidi_setPara(bidi, reinterpret_cast<const UChar*>(chs), n, dir, NULL, &status);
             if (U_SUCCESS(status)) {
                 for (int i = 0; i < n; ++i) {
                   info[i] = ubidi_getLevelAt(bidi, i);