long double aligned at 8-byte ok on Linux on POWER

IBMs response to PMR 04669,7TD,000 confirms that 8-byte alignment
returned from standard malloc() is fine for long double on Linux
on POWER.

This was the response from the IBM ToolChain team:

The "IBM long double" is implemented as a pair of double floats. The
default behavior is to use normal load float double / store float double
operations in pairs.

As such double word alignment is sufficient for IBM long double. But for
optimal load/store performance we prefer quadword alignment.

If you are concerned about the alignment from libc malloc you can try
the tcmalloc included in the AT mcore-libc RPM. tcmalloc will return
quadword aligned storage for both -m32 and -m64.