travis: increase ccache size for linux jobs

.travis.compiler.sh

@@ -22,7 +22,7 @@ if [[ "${TRAVIS_OS_NAME}" == 'linux' ]]; then
   exclude_modules;
   if which ccache ; then
     CMAKE_OPT="${CMAKE_OPT} -DCMAKE_C_COMPILER_LAUNCHER=ccache -DCMAKE_CXX_COMPILER_LAUNCHER=ccache"
-    ccache --max-size=1200M
+    ccache --max-size=2200M
   fi
   if [[ "${CXX}" == 'clang++' ]]; then
     export CXX CC=${CXX/++/}