Rename scripts/coverity.sh to tools/coverity.sh

There are only two files in tools/, I don't think we need a separate
directory for them.

.travis.yml

@@ -96,7 +96,7 @@ jobs:
                   -v ${TOOL_BASE}:${TOOL_BASE}:ro \
                   --name travis_coverity_scan ${DOCKER_REPOSITORY}:${TRAVIS_COMMIT} bash
                 # Make sure Coverity script is executable
-              - docker cp scripts/coverity.sh travis_coverity_scan:/usr/local/bin
+              - docker cp tools/coverity.sh travis_coverity_scan:/usr/local/bin
                 # Preconfigure with meson to prevent Coverity from capturing meson metadata
                 # Set compiler flag to prevent emit failure
               - docker exec -it travis_coverity_scan sh -c "CFLAGS='-D_Float128=long\ double' meson cov-build -Dman=false"