Only enable z4l.c on Linux.

Makefile.am

@@ -31,3 +31,12 @@ ChangeLog:
 	$(CHANGELOG_CMD)
 
 dist-hook: ChangeLog INSTALL
+
+#if BUILD_Z4L
+	ztv_drv_la_LTLIBRARIES = ztv_drv.la
+	ztv_drv_la_LDFLAGS = -module -avoid-version
+	ztv_drv_ladir = @moduledir@/drivers
+
+	ztv_drv_la_SOURCES = \
+	        z4l.c
+#endif

configure.ac

@@ -114,6 +114,16 @@ AC_SUBST([XORG_CFLAGS])
 AC_SUBST([moduledir])
 AC_SUBST([AMD_CFLAGS])
 
+case $host_os in
+  *linux*)
+	BUILD_Z4L=yes
+  ;;
+  *)
+	BUILD_Z4l=no
+  ;;
+esac
+
+AM_CONDITIONAL(BUILD_Z4L, [test "x$BUILD_Z4L" = xyes]) 
 is386=false
 
 case $host_cpu in