Add --enable-libxml2 to match repository package

References
----------
https://git.archlinux.org/svntogit/packages.git/commit/trunk?h=packages/ffmpeg&id=8aef847cff420afdb0be3fb18510bc901d39aca9
https://bugs.archlinux.org/task/56886

.SRCINFO

@@ -1,9 +1,9 @@
 # Generated by mksrcinfo v8
-# Thu Jan  4 14:14:36 UTC 2018
+# Thu Jan  4 14:25:01 UTC 2018
 pkgbase = ffmpeg-git
 	pkgdesc = Complete solution to record, convert and stream audio and video (git version)
-	pkgver = 3.4.r86991.g16efcfe413
-	pkgrel = 2
+	pkgver = 3.5.r89688.g1b283c4a0d
+	pkgrel = 1
 	url = http://www.ffmpeg.org/
 	arch = i686
 	arch = x86_64
@@ -33,6 +33,7 @@ pkgbase = ffmpeg-git
 	depends = libwebp
 	depends = libx11
 	depends = libxcb
+	depends = libxml2
 	depends = opencore-amr
 	depends = openjpeg2
 	depends = opus

PKGBUILD

@@ -4,8 +4,8 @@
 # Contributor: DrZaius <lou at fakeoutdoorsman.com>
 
 pkgname=ffmpeg-git
-pkgver=3.4.r86991.g16efcfe413
-pkgrel=2
+pkgver=3.5.r89688.g1b283c4a0d
+pkgrel=1
 pkgdesc='Complete solution to record, convert and stream audio and video (git version)'
 arch=('i686' 'x86_64')
 url='http://www.ffmpeg.org/'
@@ -13,8 +13,8 @@ license=('GPL3')
 depends=('alsa-lib' 'bzip2' 'fontconfig' 'fribidi' 'glibc' 'gmp' 'gnutls' 'gsm'
          'jack' 'lame' 'libavc1394' 'libiec61883' 'libmodplug' 'libpulse'
          'libraw1394' 'libsoxr' 'libssh' 'libtheora' 'libvdpau' 'libwebp'
-         'libx11' 'libxcb' 'opencore-amr' 'openjpeg2' 'opus' 'sdl2' 'speex'
-         'v4l-utils' 'xz' 'zlib'
+         'libx11' 'libxcb' 'libxml2' 'opencore-amr' 'openjpeg2' 'opus' 'sdl2'
+         'speex' 'v4l-utils' 'xz' 'zlib'
          'libass.so' 'libbluray.so' 'libfreetype.so' 'libva-drm.so' 'libva.so'
          'libva-x11.so' 'libvidstab.so' 'libvorbisenc.so' 'libvorbis.so'
          'libvpx.so' 'libx264.so' 'libx265.so' 'libxvidcore.so')
@@ -79,6 +79,7 @@ build() {
         --enable-libx264 \
         --enable-libx265 \
         --enable-libxcb \
+        --enable-libxml2 \
         --enable-libxvid \
         --enable-shared \
         --enable-version3