Use bintray snapshots

gemlib needs mintlib's compiler.h at least.

Author: mikrosk

Diff for: .travis.yml

@@ -22,6 +22,8 @@ env:
 
 # If before_install, install or before_script return a non-zero exit code, the build is errored and stops immediately.
 before_install:
+  # get rid of possibly outdated dependencies
+  - sudo dpkg --remove --force-depends mintlib-m68k-atari-mint pml-m68k-atari-mint
   - wget -q -O - https://github.com/freemint/travis-scripts/archive/master.tar.gz | tar xzf - --strip-components=1 -C .travis
   - if [ -x .travis/before_install.sh ]; then ./.travis/before_install.sh; else true; fi
 

Diff for: .travis/install.sh

@@ -0,0 +1,6 @@
+#!/bin/bash -eux
+# -e: Exit immediately if a command exits with a non-zero status.
+# -u: Treat unset variables as an error when substituting.
+# -x: Display expanded script commands
+
+./install_bintray.sh mintlib