A (somewhat) strange Sparc library issue...

[John Carr]

AIX has separate libraries for 128 bit floating point, for example
libc128.a instead of libc.a.  Compilers have switches to select 64 bit
long doubles or 128 bit long doubles and automatically link the
correct version of libc.

Unfortunately, they don't seem likely ever to complete a transition to
128 bit long double.  The current dual-library system has been in
place for at least 5 years.