travis: no out-of-source builds for coveralls

.travis.yml

@@ -22,9 +22,9 @@ script:
         pip install --user cpp-coveralls;
     else
         export TRAVIS_COVERALLS=OFF;
+        mkdir build && cd build;
     fi
   - echo TRAVIS_COVERALLS=$TRAVIS_COVERALLS
-  - mkdir build && cd build
   - cmake .. -G "Unix Makefiles" 
              -DCMAKE_DEBUG_POSTFIX=_d 
              -DCMAKE_BUILD_TYPE=$TRAVIS_BUILD_TYPE 
@@ -32,7 +32,7 @@ script:
              -DGMIO_BUILD_STRICT_C90=$TRAVIS_STRICT_C90
              -DGMIO_BUILD_TESTS_FAKE_SUPPORT=ON
              -DGMIO_BUILD_TESTS_COVERALLS=$TRAVIS_COVERALLS
-             -DCMAKE_INSTALL_PREFIX=../install
+             -DCMAKE_INSTALL_PREFIX=install
   - make -j4
   - if [ "${TRAVIS_MAKE_CHECK}" = "ON" ]; then
         make check;