[travis] avoid clean for now to speed up run times - refs #298 [skip ci]

.travis.yml

@@ -33,9 +33,7 @@ before_script:
 - if [[ ${CXX} == "clang++" ]]; then export LDFLAGS="${LDFLAGS}"; export CXXFLAGS="-Wno-unknown-warning-option -Wno-unused-local-typedefs -Wno-unknown-pragmas ${CXXFLAGS}"; fi
 script:
 - make llmr BUILDTYPE=${BUILDTYPE}
-- make clean
 - make linux BUILDTYPE=${BUILDTYPE}
-- make clean
 - make run-tests BUILDTYPE=${BUILDTYPE}
 # TODO - port to linux
 #- make run-headless-test BUILDTYPE=${BUILDTYPE}