When the data directory contained a symbolic link to another
file system, and the DATA or INDEX DIRECTORY clause of a
CREATE TABLE statement referred to a subdirectory of the data
directory, this was accepted.
      
The problem was the use of a table file path name, which included
the table name without an extension, for the comparison against
the data directory path name. This was almost always a
non-existent file. The internal algorithm failed to resolve
symbolic links for non-existent files. So we compared unrelated
path names.
      
Fixed by truncating the table name from the path before resolving
symlinks. If this is also a non-existent path, the creation of
the table will fail anyway.

Backport to 5.6.0.    6.0-codebase revid: 2599.60.1