Factorize the common code from svn_path_remove_component and svn_path_dirname.  Also, fix a whitespace formatting issue introduced in r10135.  
Factorize the common code from svn_path_remove_component and
svn_path_dirname.  Also, fix a whitespace formatting issue introduced
in r10135.  

Patch by: Klaus Rennecke <kre@tigris.org> 
(Tweaked by me: whitespace fix and docstring addition.)

* subversion/libsvn_subr/path.c
  (previous_segment): New factorized routine that finds the end of the
    previous path segment.
  (svn_path_remove_component, svn_path_dirname): Utilize the newly
    created previous_segment.
  (svn_path_canonicalize): Add whitespace after a while statement.

jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion