targets/vdpau-nouveau: convert to static/shared pipe-drivers

Create a single library (for the vdpau api) thus reducing
the overall size of mesa. Current commit converts
vdpau-nouveau, with upcomming commits handling the rest.

The library can be built with the relevant pipe-drivers
statically linked in, or loaded as shared modules.
Currently we default to static.

Add SPLIT_TARGETS to guard the other VL targets.

Note: symlink handling is rather ugly and will need an
update to work with BSD and other non-linux platforms.

v2: Split the conversion into per-target basis.

Cc: Maarten Lankhorst <maarten.lankhorst@canonical.com>
Cc: Ilia Mirkin <imirkin@alum.mit.edu>
Signed-off-by: Emil Velikov <emil.l.velikov@gmail.com>
Tested-by: Thomas Helland <thomashelland90 at gmail.com>
diff --git a/configure.ac b/configure.ac
index 8f86154..1750a2b 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1417,6 +1417,7 @@
     PKG_CHECK_MODULES([VDPAU], [vdpau >= $VDPAU_REQUIRED x11-xcb xcb-dri2 >= $XCBDRI2_REQUIRED],
                       [VDPAU_LIBS="`$PKG_CONFIG --libs x11-xcb xcb-dri2`"])
     GALLIUM_STATE_TRACKERS_DIRS="$GALLIUM_STATE_TRACKERS_DIRS vdpau"
+    enable_gallium_loader=yes
 fi
 AM_CONDITIONAL(HAVE_ST_VDPAU, test "x$enable_vdpau" = xyes)
 
@@ -1967,7 +1968,7 @@
             PKG_CHECK_MODULES([NOUVEAU], [libdrm_nouveau >= $LIBDRM_NOUVEAU_REQUIRED])
             gallium_require_drm_loader
             GALLIUM_DRIVERS_DIRS="$GALLIUM_DRIVERS_DIRS nouveau"
-            gallium_check_st "nouveau/drm" "dri-nouveau" "" "xvmc-nouveau" "vdpau-nouveau" "omx-nouveau"
+            gallium_check_st "nouveau/drm" "dri-nouveau" "" "xvmc-nouveau" "vdpau/nouveau" "omx-nouveau"
             DRICOMMON_NEED_LIBDRM=yes
             ;;
         xfreedreno)
@@ -2225,7 +2226,7 @@
 		src/gallium/targets/radeonsi/dri/Makefile
 		src/gallium/targets/radeonsi/omx/Makefile
 		src/gallium/targets/radeonsi/vdpau/Makefile
-		src/gallium/targets/vdpau-nouveau/Makefile
+		src/gallium/targets/vdpau/Makefile
 		src/gallium/targets/xa/Makefile
 		src/gallium/targets/xa/xatracker.pc
 		src/gallium/targets/xvmc-nouveau/Makefile