fix .clang-format-ignore script for travis

Author: Daniel Kroening

.travis.yml

@@ -17,8 +17,8 @@ jobs:
       script: |
         clang-format-7 --version
         # build a pathspec that excludes the files in .clang-format-ignore
-        while read file ; do echo EXCLUDES+="':(top,exclude)$file' " ; done < .clang-format-ignore
-        git-clang-format-7 --binary clang-format-7 "${TRAVIS_BRANCH}" -- $EXCLUDES
+        while read file ; do EXCLUDES+=" ':(top,exclude)${file}'" ; done < .clang-format-ignore
+        git-clang-format-7 --binary clang-format-7 "${TRAVIS_BRANCH}" -- ${EXCLUDES}
         git diff > formatted.diff
         if [[ -s formatted.diff ]] ; then
           echo 'Formatting error! The following diff shows the required changes'