ffmpeg: Update and link as console application

SDL and libcaca automatically adds `-mwindows`, treating the ffmpeg.exe as a
GUI application while at the same time making stderr go to NUL.

Found-by: Bill Westrup <wwestrup@vsscorp.com>
See: http://lists.nongnu.org/archive/html/mingw-cross-env-list/2014-12/msg00018.html
Signed-off-by: Timothy Gu <timothygu99@gmail.com>

src/ffmpeg.mk

@@ -3,8 +3,8 @@
 
 PKG             := ffmpeg
 $(PKG)_IGNORE   :=
-$(PKG)_VERSION  := 2.4.4
-$(PKG)_CHECKSUM := c0a0829fbb4cf423eed77f39d3661d1a34ac7c35
+$(PKG)_VERSION  := 2.5
+$(PKG)_CHECKSUM := ec0111e8298bdb2291d82e3b4f67354ba48fab19
 $(PKG)_SUBDIR   := $(PKG)-$($(PKG)_VERSION)
 $(PKG)_FILE     := $(PKG)-$($(PKG)_VERSION).tar.bz2
 $(PKG)_URL      := http://www.ffmpeg.org/releases/$($(PKG)_FILE)
@@ -45,6 +45,7 @@ define $(PKG)_BUILD
         --enable-avresample \
         --enable-gpl \
         --enable-version3 \
+        --extra-libs='-mconsole' \
         --enable-avisynth \
         --enable-gnutls \
         --enable-libass \