qemu: explicitly disable dependency on libpmem, libudev, libxml2

Supersedes openwrt/packages#8571

Reported-by: Rosen Penev rosenp@gmail.com
Signed-off-by: Yousong Zhou <yszhou4tech@gmail.com>

utils/qemu/patches/0002-configure-allow-enabling-disabling-libudev-from-comm.patch

@@ -0,0 +1,25 @@
+From 4d7955f069922c482886e03e5cd352281dbce146 Mon Sep 17 00:00:00 2001
+From: Yousong Zhou <yszhou4tech@gmail.com>
+Date: Tue, 2 Apr 2019 06:31:31 +0000
+Subject: [PATCH 2/4] configure: allow enabling/disabling libudev from command
+ line
+
+---
+ configure | 4 ++++
+ 1 file changed, 4 insertions(+)
+
+diff --git a/configure b/configure
+index d274df816c..a138faeb72 100755
+--- a/configure
++++ b/configure
+@@ -1491,6 +1491,10 @@ for opt do
+   ;;
+   --disable-libpmem) libpmem=no
+   ;;
++  --enable-libudev) libudev=yes
++  ;;
++  --disable-libudev) libudev=no
++  ;;
+   --disable-fortify-source) fortify_source="no"
+   ;;
+   *)