Fix const issues in preparation for libcxx rebase.

Change-Id: I2a939c87af3ef9881d9c806ba374185bd31a4954
diff --git a/opengl/system/GLESv2_enc/GL2Encoder.cpp b/opengl/system/GLESv2_enc/GL2Encoder.cpp
index 0d0868f..7669235 100755
--- a/opengl/system/GLESv2_enc/GL2Encoder.cpp
+++ b/opengl/system/GLESv2_enc/GL2Encoder.cpp
@@ -936,7 +936,7 @@
     if (needLocationWAR) {
         int namelen = strlen(name);
         if (name[namelen-1] == ']') {
-            char *brace = strrchr(name,'[');
+            const char *brace = strrchr(name,'[');
             if (!brace || sscanf(brace+1,"%d",&arrIndex) != 1) {
                 return -1;
             }