Long doubles are forbidden by PPC64 spec

[Jeff Johnson]

LSB 4.0 Release Notes reads:

Updated Support for PowerPC

Support for the new size of long doubles has been added to the SDK.
Applications built with the SDK to target 4.0 will use the new size;
applications built to target the 3.x versions will continue to use the old
size.

At the same time LSB Core 4.0 PPC64 specification says:

8.1.4. Fundamental Types

LSB-conforming applications shall use the fundamental types as defined in
Chapter 3 of the 64-bit PowerPC™ ELF ABI Supplement.

LSB-conforming applications shall not use the long double fundamental type.