configure: Remove --enable-rw-rootfs detect using /etc/fstab instead

This patch removes the --enable-rw-rootfs build flag.  Like OpenRC we
now check /etc/fstab instad; if `/` is listed *and* doesn't have the
`ro` flag set, we remount / read-write.

Signed-off-by: Joachim Nilsson <troglobit@gmail.com>

contrib/debian/build.sh

@@ -22,7 +22,7 @@ echo
 # The plugins are optional, but you may need D-Bus and X11 if you want
 # to run X-Window, the other configure flags are however required.
 ./configure									\
-    --enable-rw-rootfs                --enable-progress				\
+                                      --enable-progress				\
     --enable-dbus-plugin              --enable-x11-common-plugin		\
     --enable-alsa-utils-plugin        --enable-inetd-echo-plugin		\
     --enable-inetd-chargen-plugin     --enable-inetd-daytime-plugin		\