move checkstyle.xml to build-tools

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/proxy/branches/version-2.0-work@967242 13f79535-47bb-0310-9956-ffa450edef68
diff --git a/checkstyle.xml b/build-tools/src/main/resources/org/apache/commons/proxy2/checkstyle.xml
similarity index 100%
rename from checkstyle.xml
rename to build-tools/src/main/resources/org/apache/commons/proxy2/checkstyle.xml