games-emulation/vbam: Pin ffmpeg back to version 3

It doesn't build with ffmpeg 4, the dependency is optional, and
upstream don't appear to be in a hurry to fix it.

Closes: https://bugs.gentoo.org/654176
Package-Manager: Portage-2.3.48, Repoman-2.3.10

games-emulation/vbam/vbam-2.0.2.ebuild

@@ -30,7 +30,7 @@ RDEPEND="
 	sys-libs/zlib:=
 	virtual/glu
 	virtual/opengl
-	ffmpeg? ( media-video/ffmpeg:= )
+	ffmpeg? ( =media-video/ffmpeg-3*:= )
 	lirc? ( app-misc/lirc )
 	nls? ( virtual/libintl )
 	wxwidgets? (

games-emulation/vbam/vbam-9999.ebuild

@@ -30,7 +30,7 @@ RDEPEND="
 	sys-libs/zlib:=
 	virtual/glu
 	virtual/opengl
-	ffmpeg? ( media-video/ffmpeg:= )
+	ffmpeg? ( =media-video/ffmpeg-3*:= )
 	lirc? ( app-misc/lirc )
 	nls? ( virtual/libintl )
 	wxwidgets? (