GLES backend misses runtime shader compiler

The GLES support at Evas brings two different flavors, one with runtime shader compiler and the other without. By default it'll build without runtime shader compiler, making it not use something that's available in most chips (like SGX and Tegra 2), and that helps a lot.

So to properly have the GLES support, with best performance available, we should enable the support for the runtime shader compiler at evas during build-time (--enable-gles-variety-sgx).

From evas configure.ac:
       [Please enable just 1 OpenGL-ES flavor. Choices are:
          --enable-gles-variety-sgx (Most GL-ES2 GPUs with shader compiler)
          --enable-gles-variety-s3c6410 (s3c6410 with offline shader compiler)
        You will also need to enable the OpenGL engine for X11 with:
          --enable-gl-x11]