Protocol_cursor class and sql-common/ directory


Makefile.am:
  pack.c added to linked sources
include/mysql.h:
  net_field_length_ll declaration added
include/mysql_com.h:
  net_field_length declaration added
libmysql/Makefile.am:
  sql-common files symlinked
libmysql/Makefile.shared:
  pack.lo target added
libmysql/libmysql.c:
  net_field_length removed from here
sql/Makefile.am:
  pack.c added to the sources
sql/mini_client.cc:
  mc_net_field_length functions replaced with net_field_length
sql/protocol.h:
  Protocol_cursor class added