Update GLES codegen to be in sync with frameworks/base

Patch from synergydev with commit-id 01994c79 changed
core/jni/com_google_android_gles_jni_GLImpl.cpp in the
frameworks/base. However the corresponding code snippet
in frameworks/native was not updated. This patch addresses
the issue.

Change-Id: I89c3d88de832efc8cbbe682c8a7ff7dfbef99db3
Signed-off-by: Ashok Bhat <ashok.bhat@arm.com>

opengl/tools/glgen/stubs/jsr239/GLCHeader.cpp

@@ -182,7 +182,7 @@ getDirectBufferPointer(JNIEnv *_env, jobject buffer) {
             if (array) {
                 releasePointer(_env, array, buf, 0);
             }
-            buf = buf + offset;
+            buf = (char*)buf + offset;
         } else {
             jniThrowException(_env, "java/lang/IllegalArgumentException",
                               "Must use a native order direct Buffer");