long double format on I!64

[Jim Wilson]

ia64-linux uses a long double with 80-bits of info stored in a 128-bit
slot.  The 80-bit format is used for compatibility with x86 systems.
The 128-bit slot is used to make alignment/padding simpler.  The first
ten bytes are the FP value, the last 6 bytes are the padding.  This is
true for both big and little endian.

ia64-hpux however uses an actual 128-bit long double.  This is for
compatibility with hppa-hpux systems.  I don't have access to ia64-hpux,
so I can't help you with this.

Jim