glProgramBinary may fail if the driver is incompatible with the binary
that is being loaded. After this ANGLE falls back to recompiling the
GLSL program from source, but this requires that the ProgramGL object
used is still valid after a failed glProgramBinary call.

Don't delete the GL program after a failed glProgramBinary call so
that the fallback works as intended.

BUG=angleproject:2751

Change-Id: I55c19d71414163b1cd9f898f304e4aa7052f6b16
Reviewed-on: https://chromium-review.googlesource.com/1160540Reviewed-by: Geoff Lang <geofflang@chromium.org>
Commit-Queue: Olli Etuaho <oetuaho@nvidia.com>