www/c-icap: update to 0.6.3

Switch c-icap server from branch 5.X to 6.X

Full changelog:
  0.6.2 changelog:
   - link c-icap server binaries with the math library
   - Add new records to c-icap.magic, which are required for virus
     scan service.
  0.6.1 changelog:
   - Internal web server for use with services
   - Improved statistics and statistics API
   - Support histograms creation from statistic values
   - The pthread inter-process locking scheme
   - The new lmdb_tables module, to provide support for lmdb based
     lookup tables
   - Extended changes and fixes to the ldap support module
   - The ci_server_shared_memblob_* functions to access small memory
     blocks which are shared across c-icap processes.
   - Many fixes/improvements and new API functions.
  0.6.0 changelog:
   - Support for lmdb based databases as an alternate to BerkeleyDB.
   - Improved info service to show c-icap statistics
   - Internal web server
   - The pthread inter-process locking scheme.
   - New development APIs: c-icap server shared memblocks, flat arrays
   - C-icap statistics for server and services: Time based statistics,
     histograms, API to retrieve statistics values, improved update operations