Bring back smbclient support (fixed by upstream)

smbclient support was previously removed[1] due to a build failure
with samba 4.9. It looks like that the recently released samba 4.13
fixed[2][3] the issue and now ffmpeg is building fine with it.

References
----------
[1] https://aur.archlinux.org/cgit/aur.git/commit/?h=ffmpeg-full&id=f12ec9acea516c773870506abae2b0e7fd2a1067
[2] https://github.com/samba-team/samba/pull/212/
[3] https://github.com/samba-team/samba/commit/1114b02a72ce0c86a5301816560d270ec47f8be3

.SRCINFO

@@ -1,7 +1,7 @@
 pkgbase = ffmpeg-full
 	pkgdesc = Complete solution to record, convert and stream audio and video (all possible features including libfdk-aac)
 	pkgver = 4.3.1
-	pkgrel = 7
+	pkgrel = 8
 	url = https://www.ffmpeg.org/
 	arch = x86_64
 	license = custom: nonfree and unredistributable
@@ -55,6 +55,7 @@ pkgbase = ffmpeg-full
 	depends = librsvg
 	depends = rubberband
 	depends = rtmpdump
+	depends = smbclient
 	depends = snappy
 	depends = libsoxr
 	depends = speex