remove travis build file, hasn’t actually ran for a long time

.travis.yml

@@ -1,15 +0,0 @@
-# Freedoom isn't really C, but we need to specify a language:
-language: c
-compiler: gcc
-
-# These are the build-deps from the Debian Freedoom package:
-addons:
-    apt:
-        packages:
-        - deutex
-        - gsfonts
-        - imagemagick
-        - python
-
-script: make
-