RDP compositor take 6

This patch is the 6th version of the FreeRDP based compositor.
Changes from last version:
 * use pixman_image_get_stride() when appropriate
 * always realloc

Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>
diff --git a/configure.ac b/configure.ac
index 355063d..ed06d0b 100644
--- a/configure.ac
+++ b/configure.ac
@@ -168,6 +168,13 @@
   PKG_CHECK_MODULES([FBDEV_COMPOSITOR], [libudev >= 136 mtdev >= 1.1.0])
 ])
 
+AC_ARG_ENABLE([rdp-compositor], [  --enable-rdp-compositor],,
+              enable_rdp_compositor=no)
+AM_CONDITIONAL([ENABLE_RDP_COMPOSITOR],
+               [test x$enable_rdp_compositor = xyes])
+if test x$enable_rdp_compositor = xyes; then
+  PKG_CHECK_MODULES(RDP_COMPOSITOR, [freerdp >= 1.1.0])
+fi
 
 AC_ARG_WITH(cairo-glesv2,
             AS_HELP_STRING([--with-cairo-glesv2],