Fix to issue #114: FORMAT_COMPILER_TARGET_ALT is being used now for the OpenGL cases

Problem: at the stage of the o2em building, the "-opengl" suffix was
added a lot of times to FORMAT_COMPILER_TARGET variable breaking the platform
detection in the o2em Makefile, preventing the fpic option to be added to the
command line of the compiler
Revert "Fix to issue #114: FORMAT_COMPILER_TARGET_ALT is being used now for the OpenGL cases"

This reverts commit c1f950767e20f79a0ac47a1be4a0530c75b09ad1.
Alternative fix to issue #114: in the c1f950767e20 commit, I assumed some things
which weren't right. This commit just makes the minimal changes to let o2em
compile successfully.
Merge pull request #125 from tomgar/fix-o2em-compilation

Fix to issue #114: FORMAT_COMPILER_TARGET_ALT is being used now for the ...