.travis.yml: added "make clean" before versionsTest
diff --git a/.travis.yml b/.travis.yml
index 5e499ab..972c1b4 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -44,7 +44,7 @@
             - qemu-user-static
     - os: linux
       sudo: required
-      env: PLATFORM="Ubuntu 12.04" CMD="make -C programs zstd-small && make -C programs zstd-decompress && make -C programs zstd-compress && make -C tests versionsTest"
+      env: PLATFORM="Ubuntu 12.04" CMD="make -C programs zstd-small && make -C programs zstd-decompress && make -C programs zstd-compress && make clean && make -C tests versionsTest"
     - os: linux
       sudo: required
       env: PLATFORM="Ubuntu 12.04" CMD="make asan32"