Use svn_cstring_atoui64() to parse and validate module parameters.
Use svn_cstring_atoui64() to parse and validate module parameters.

* subversion/mod_dav_svn/mod_dav_svn.c
  (parse_number): drop
  (SVNInMemoryCacheSize_cmd): use svn_cstring_atoui64

Suggested by: stsp

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