Various C99 compliance fixes.

compiler/C_CodeGen.jrag

examples/twoway/Makefile

lib/c/Makefile

lib/c/labcomm_decoder.c

lib/c/labcomm_default_scheduler.c

lib/c/labcomm_pthread_scheduler.c

lib/c/labcomm_scheduler.c

lib/c/labcomm_scheduler.h

lib/c/labcomm_scheduler_private.h

lib/c/labcomm_time.c

lib/c/test/test_labcomm.c

test/Makefile