automake: use static llvm for make distcheck

With llvm 3.7 semi-dropping the autoconf build, we rely on their cmake
build. With the latter of which annoyingly using another (busted?)
SONAME.

Signed-off-by: Emil Velikov <emil.l.velikov@gmail.com>
diff --git a/Makefile.am b/Makefile.am
index 149610c..a9ed31e 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -32,6 +32,7 @@
 	--enable-vdpau \
 	--enable-xa \
 	--enable-xvmc \
+	--disable-llvm-shared-libs \
 	--with-egl-platforms=x11,wayland,drm \
 	--with-dri-drivers=i915,i965,nouveau,radeon,r200,swrast \
 	--with-gallium-drivers=i915,ilo,nouveau,r300,r600,radeonsi,freedreno,svga,swrast