Fix various problems with the timer code. * SDL_timer_running wasn't always updated correctly. * Fixed occasional crash in SDL_SetTimer() when clearing threaded timers * It was possible to get both the timer thread and event thread running * Other misc. cleanup

## Makefile.am for SDL using the IRIX DMedia sound driver

noinst_LTLIBRARIES = libaudio_dmedia.la
libaudio_dmedia_la_SOURCES = $(SRCS)

# The SDL audio driver sources
SRCS =	SDL_irixaudio.c	\
	SDL_irixaudio.h