(compiler issue ?)

Problem:

Improper compile-time flags on AIX prevented use of files > 2 GB. This
resulted in Max_data_length being truncated to 2 GB by MyISAM code.

Solution:

Reverted large-file changes from the fix for bug10776. We need to define
_LARGE_FILES on AIX to have support for files > 2 GB.

 Since _LARGE_FILE_API is incompatible with _LARGE_FILES and may be
automatically defined by including standards.h, we also need a
workaround to avoid this conflict.