Perform some cleanup of bluegene plugin for clean build without BGL APIs.

src/plugins/select/bluegene/bgl_job.c

src/plugins/select/bluegene/bluegene.c

src/plugins/select/bluegene/bluegene.h

src/plugins/select/bluegene/select_bluegene.c

src/plugins/select/bluegene/state_test.c