separate PANDORA and TEGRA port better

Preparation of updating the pandora port, the update requires a
different eglport.[c,h] which might hurt the existing TEGRA port. Create
a copy of the old eglport and wire it in TEGRA specifically.
pandora port, step 1: updated eglport

first step of the changes by pickle: use a more recent version of
eglport, also available via
http://sourceforge.net/p/eglport/code-0/HEAD/tree/trunk/src/
2nd part of pandora port changes

original diff from pickle, remaining TODOs:
1) make sure things are separated from "the rest" (no breakage in
original code)
2) update makefile to write correct USE_GLES? variable
fix compiler guard

now compilation with Makefile.pandora and USE_GLES2 should work for this
file
cleanup of the patch from pickle

removed everything which is not built anyway when the USE_GLES1 flag is
active, the parts which were commented out would not work when building
"real" GLES2 though...

the system should now behave as it did before the changes unless the
pandora port is built, this one still requires a makefile change to
build correctly (next commit)
add USE_GLES1 var to pandora makefile