recipes: add x11 to required DISTRO_FEATURES

* it's not complete, but recipes depending on virtual/libx11 are easiest
  to spot, I've long list of PNBLACKLIST for all recipes which cannot
  be built in distro without x11 in DISTRO_FEATURES

(From OE-Core rev: 78d269fa9a586e24ef058ba5315c696f15935f56)

Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/recipes-graphics/packagegroups/packagegroup-core-x11-base.bb

@@ -3,7 +3,9 @@ DESCRIPTION = "Packages required to set up a basic working X11 session"
 LICENSE = "MIT"
 PR = "r1"
 
-inherit packagegroup
+inherit packagegroup distro_features_check
+# rdepends on matchbox-wm
+REQUIRED_DISTRO_FEATURES = "x11"
 
 RDEPENDS_${PN} = "\
     packagegroup-core-x11-xserver \

meta/recipes-graphics/packagegroups/packagegroup-core-x11-xserver.bb

@@ -8,7 +8,9 @@ PR = "r40"
 
 PACKAGE_ARCH = "${MACHINE_ARCH}"
 
-inherit packagegroup
+inherit packagegroup distro_features_check
+# rdepends on XSERVER
+REQUIRED_DISTRO_FEATURES = "x11"
 
 XSERVER ?= "xserver-xorg xf86-video-fbdev xf86-input-evdev"
 XSERVERCODECS ?= ""

meta/recipes-graphics/packagegroups/packagegroup-core-x11.bb

@@ -5,7 +5,9 @@
 LICENSE = "MIT"
 PR = "r40"
 
-inherit packagegroup
+inherit packagegroup distro_features_check
+# rdepends on x11-common
+REQUIRED_DISTRO_FEATURES = "x11"
 
 PACKAGES = "${PN} ${PN}-utils"