depends: libX11: Make package headers-only

We're no longer building QT with libX11/XLib, however, libX11/XLib
headers are still required for parts of QT. In this commit we add a
minimal configure.ac for libX11/XLib that is headers-only.

This change allows us to remove all of libX11/XLib's dependencies.

depends/patches/libX11/configure.ac

@@ -0,0 +1,6 @@
+AC_PREREQ([2.60])
+AC_INIT([libX11], [1.6.2],
+        [https://bugs.freedesktop.org/enter_bug.cgi?product=xorg], [libX11])
+AM_INIT_AUTOMAKE([foreign])
+AC_CONFIG_FILES([include/Makefile])
+AC_OUTPUT