Include coverage in Travis build only for GCC

.travis.yml

@@ -11,9 +11,11 @@ before_script:
   - mkdir build
   - cd build
   - export BIN_DIR=$PWD
-  - cmake -D CMAKE_CXX_FLAGS:STRING="-std=c++0x --coverage" -D CMAKE_BUILD_TYPE:STRING=Debug ../
+  - CMAKE_CXX_FLAGS="-std=c++0x"
+  - if [ "${CC}" = "gcc" ]; then CMAKE_CXX_FLAGS="${CMAKE_CXX_FLAGS} --coverage"; fi
+  - cmake -D CMAKE_CXX_FLAGS:STRING="${CMAKE_CXX_FLAGS}" -D CMAKE_BUILD_TYPE:STRING=Debug ../
 script:
   - make -j $(nproc)
   - ../tests/run.sh
 after_success:
-  - coveralls --exclude examples --exclude tests --exclude-pattern '.*CMake[^/]+\.c(?:pp)?' --exclude-pattern "/usr/.*" --root=${SRC_DIR} --build-root ${BIN_DIR} | grep -vP "^File '.*'$" | grep -vP ":creating '.*'$" | grep -vP "^Lines executed:.*" | sed '/^$/d'
+  - if [ "${CC}" = "gcc" ]; then coveralls --exclude examples --exclude tests --exclude-pattern '.*CMake[^/]+\.c(?:pp)?' --exclude-pattern "/usr/.*" --root=${SRC_DIR} --build-root ${BIN_DIR} | grep -vP "^File '.*'$" | grep -vP ":creating '.*'$" | grep -vP "^Lines executed:.*" | sed '/^$/d'; fi