depends: switch libaom to aom (aom is now in official repositories)

References
----------
https://www.archlinux.org/packages/extra/x86_64/aom/

.SRCINFO

@@ -1,7 +1,7 @@
 pkgbase = ffmpeg-full
 	pkgdesc = Complete solution to record, convert and stream audio and video (all possible features including nvenc, qsv and libfdk-aac)
 	pkgver = 4.0.1
-	pkgrel = 2
+	pkgrel = 3
 	url = http://www.ffmpeg.org/
 	arch = i686
 	arch = x86_64
@@ -21,6 +21,7 @@ pkgbase = ffmpeg-full
 	depends = gnutls
 	depends = ladspa
 	depends = libass
+	depends = aom
 	depends = libbluray
 	depends = libbs2b
 	depends = libcaca
@@ -83,7 +84,6 @@ pkgbase = ffmpeg-full
 	depends = libdrm
 	depends = libvdpau
 	depends = chromaprint-fftw
-	depends = libaom
 	depends = codec2
 	depends = flite1-patched
 	depends = libilbc