or1k: Support for softfloat to emulate hw exceptions

or1k: Support for softfloat to emulate hw exceptions

This allows the openrisc softfloat implementation to set exceptions.
This also sets the correct tininess after rounding value to be
consistent with hardware and simulator implementations.

libgcc/ChangeLog:

	* config/or1k/sfp-machine.h (FP_RND_NEAREST, FP_RND_ZERO,
	FP_RND_PINF, FP_RND_MINF, FP_RND_MASK, FP_EX_OVERFLOW,
	FP_EX_UNDERFLOW, FP_EX_INEXACT, FP_EX_INVALID, FP_EX_DIVZERO,
	FP_EX_ALL): New constant macros.
	(_FP_DECL_EX, FP_ROUNDMODE, FP_INIT_ROUNDMODE,
	FP_HANDLE_EXCEPTIONS): New macros.
	(_FP_TININESS_AFTER_ROUNDING): Change to 1.