Add a new TESTS envvar to .travis.yml to disable gtest on Ubuntu Trusty 14.04

Recent googletest doesn't compile on this old Ubunty

.travis.yml

@@ -14,6 +14,7 @@ env:
     - ASAN=ON
     - INTERNAL_SQLITE=ON
     - VALGRIND=OFF
+    - TESTS=ON
 
 # Build variants (should test a reasonable number of combination of CMake options)
 jobs:
@@ -69,6 +70,7 @@ jobs:
     - dist: trusty
       env:
         - cc=gcc cxx=g++
+        - TESTS=OFF
 
     ##########################################################################
     # Clang on Linux
@@ -88,6 +90,7 @@ jobs:
     - dist: trusty
       env:
         - cc=clang cxx=clang++
+        - TESTS=OFF
 
     ##########################################################################
     # Clang on OSX
@@ -121,13 +124,13 @@ before_install:
 before_script:
   - mkdir build
   - cd build
-  - cmake -DCMAKE_VERBOSE_MAKEFILE=ON -DCMAKE_BUILD_TYPE=$BUILD_TYPE -DSQLITECPP_INTERNAL_SQLITE=$INTERNAL_SQLITE -DSQLITECPP_USE_ASAN=$ASAN -DSQLITECPP_USE_GCOV=$GCOV -DSQLITECPP_BUILD_EXAMPLES=ON -DSQLITECPP_BUILD_TESTS=ON ..
+  - cmake -DCMAKE_VERBOSE_MAKEFILE=ON -DCMAKE_BUILD_TYPE=$BUILD_TYPE -DSQLITECPP_INTERNAL_SQLITE=$INTERNAL_SQLITE -DSQLITECPP_USE_ASAN=$ASAN -DSQLITECPP_USE_GCOV=$GCOV -DSQLITECPP_BUILD_EXAMPLES=$TESTS -DSQLITECPP_BUILD_TESTS=$TESTS ..
 
 # build examples, and run tests (ie make & make test)
 script:
   - cmake --build .
   - export ASAN_OPTIONS=verbosity=1:debug=1
-  - ctest --verbose --output-on-failure
+  - if [[ "$TESTS" == "ON" ]]; then ctest --verbose --output-on-failure ; fi
   - if [[ "$VALGRIND" == "ON" ]]; then valgrind --leak-check=full --error-exitcode=1 bin/SQLiteCpp_example1 ; fi
   - if [[ "$VALGRIND" == "ON" ]]; then valgrind --leak-check=full --error-exitcode=1 bin/SQLiteCpp_tests ; fi