Merge remainder of r1536744 from trunk:

trigger the generation of apr_escape_test_char.h during
the build

clean the most critical gen_test_char artifacts
  (.libs still not removed)


git-svn-id: https://svn.apache.org/repos/asf/apr/apr/branches/1.5.x@1536840 13f79535-47bb-0310-9956-ffa450edef68