merge fix for STDCXX-501 to 4.2

[Martin Sebor]

I plan to merge the fix below to 4.2. The change implements
a long-awaited solution to a binary incompatibility problem
between stdcxx and code compiled with HP aCC with the -AA
option as described in STDCXX-501:

    http://issues.apache.org/jira/browse/STDCXX-501
    http://svn.apache.org/viewvc?view=rev&revision=573411

The change has been successfully tested in our nightly builds
since last Friday.

Martin