Remove and untrack generated files

* Remove generated files
* Add generated files to .gitignore
* Add a comment to the generated files so developers know which files to
  edit

Author: ctubbsii

zookeeper-client/zookeeper-client-c/.gitignore

@@ -0,0 +1,4 @@
+# Ignore generated files from the Maven build to patch the ZooKeeper version
+/CMakeLists.txt
+/configure.ac
+/include/zookeeper_version.h