travis: use clang for ffmpeg/libav compilation

I overlooked the fact that the ffmpeg/libav build system only supports `--cc`
and completly ignores $CC. Hopefully this makes the build times a little
faster.

Fixes #332

1 files changed, 1 insertions, 1 deletions

diff --git a/travis-deps b/travis-deps
index 322ddab80c..741a3d00e5 100755
--- a/travis-deps
+++ b/travis-deps
@@ -72,7 +72,7 @@ class Libav < TravisDepsBuilder
   end
 
   def configure
-    [super, "--disable-doc"].join(" ")
+    [super, "--disable-doc", "--cc=#{ENV['CC']}"].join(" ")
   end
 end