dont' use deprecated GLES20.GL_STENCIL_INDEX constant

Author: codeanticode

core/src/processing/opengl/PGLES.java

@@ -978,7 +978,7 @@ protected FontOutline createFontOutline(char ch, Object font) {
     DEPTH_COMPONENT24 = 0x81A6;
     DEPTH_COMPONENT32 = 0x81A7;
 
-    STENCIL_INDEX  = GLES20.GL_STENCIL_INDEX;
+    STENCIL_INDEX  = 6401; // GLES20.GL_STENCIL_INDEX is marked as deprecated
     STENCIL_INDEX1 = 0x8D46;
     STENCIL_INDEX4 = 0x8D47;
     STENCIL_INDEX8 = GLES20.GL_STENCIL_INDEX8;