vchoi_fork

[svn-r8844] Purpose:
    Bug fix

Description:
    The "shared" raw B-tree node can get freed before all the B-tree nodes
had been flushed out to disk and released by the cache.

Solution:
    Implement a simple reference counting wrapper for objects in the library
and use it to hold the shared raw B-tree nodes so they aren't freed before all
references to them in memory are released.

Platforms tested:
    Solaris 2.7 (arabica)
    FreeBSD 4.10 (sleipnir)
    IRIX64 6.5 (modei4)