gmp 6.0.0a make check fails with icc (Christof S?ger)

[roger golliver]

Try asking the Intel Compiler to do standards' conforming floating-point
expression evaluation.

CC="icc -fp-model precise" CXX="icpc -fp-model precise" ./configure
--enable-cxx

By default, icc's authors chose a "hope for improved performance" when
evaluating floating-point expressions, rather than standards' conformance.

Roger Golliver