Fixed again "always inline function can't be inlined" error when compiling with debug and gcc-4.2 under Snow Leopard.
Fixed a warning "suggest parentheses around && within ||".
Replaced "ifndef __APPLE__" with "ifndef DEBUG" to partially fix debug build.
Removed unneeded "ifndef __APPLE__" to partially fix debug build.
Fixed a warning "suggest parentheses around && within ||".
Temporary removed a few ASSERT() calls to allow compiling with DEBUG defined.

This requires proper solutions, but since under OSX the vnode is opaque, it will
be it bit more work than under other systems.
Fixed wrong use of ZFS_OBJ_MUTEX() calls in some ASSERT() calls.