Import swrastg the Gallium3D software rasterizer. It uses the softpipe

driver by default but can also use the llvmpipe driver that use LLVM 
for code generation if available.

Not yet linked to the build as it depends on pthreads and we don't know
yet how to handle the switch from the default 'swrast' driver, but having
it in tree will help testing and debugging the remaining issues.

Tested by ajacoutot@ and matthieu@, looks ok to matthieu@

lib/libGL/dri/swrastg/Makefile

@@ -0,0 +1,54 @@
+#	$OpenBSD: Makefile,v 1.1.1.1 2012/07/13 12:54:20 mpi Exp $
+
+LIB=	swrast_dri.so
+
+GALLIUM=	${.CURDIR}/../../../../dist/Mesa/src/gallium
+
+CPPFLAGS= \
+	-I${GALLIUM}/include \
+	-I${GALLIUM}/auxiliary \
+	-I${GALLIUM}/drivers \
+	-I${GALLIUM}/winsys/sw/dri
+
+DRIVER_LIBS= \
+	../../gallium/drivers/trace/libtrace_pic.a \
+	../../gallium/drivers/rbug/librbug_pic.a \
+	../../gallium/drivers/softpipe/libsoftpipe_pic.a
+
+.ifdef XENOCARA_HAVE_LLVM
+DRIVER_LIBS+=	../../gallium/drivers/llvmpipe/libllvmpipe_pic.a
+.endif
+
+DRIVER_DEFINES = \
+	-D__NOT_HAVE_DRM_H \
+	-DGALLIUM_SOFTPIPE \
+	-DGALLIUM_RBUG \
+	-DGALLIUM_TRACE
+
+SWRAST_COMMON_SOURCES = \
+	utils.c \
+	drisw_util.c \
+	xmlconfig.c
+
+DRIVER_SOURCES = \
+	swrast_drm_api.c
+
+SRCS = \
+	${SWRAST_COMMON_SOURCES} \
+	${DRIVER_SOURCES}
+
+LDADD=	../../gallium/libmesagallium/libmesagallium_pic.a \
+	../../glsl/libglsl/libglsl_pic.a \
+	${DRIVER_LIBS} \
+	../../gallium/libgallium/libgallium_pic.a \
+	-L${X11BASE}/lib -lexpat -lm -lstdc++ -lc -pthread
+# XXX This is wrong but the gallium drivers depend on libpthread
+# and some bindings still fail even with the LD_PRELOAD hack when
+# starting X.
+#LDADD+= -lpthread
+DPADD=	../../gallium/libmesagallium/libmesagallium_pic.a
+
+.include "../../gallium/Makefile.inc"
+.include <bsd.xorg.mk>
+
+.PATH: ${GALLIUM}/targets/dri-swrast