Add pre_reload splitter to detect fp min/max pattern.

We have ix86_expand_sse_fp_minmax to detect min/max sematics, but
it requires rtx_equal_p for cmp_op0/cmp_op1 and if_true/if_false, for
the testcase in the PR, there's an extra move from cmp_op0 to if_true,
and it failed ix86_expand_sse_fp_minmax.

This patch adds pre_reload splitter to detect the min/max pattern.

Operands order in MINSS matters for signed zero and NANs, since the
instruction always returns second operand when any operand is NAN or
both operands are zero.

gcc/ChangeLog:

	PR target/110170
	* config/i386/i386.md (*ieee_max<mode>3_1): New pre_reload
	splitter to detect fp max pattern.
	(*ieee_min<mode>3_1): Ditto, but for fp min pattern.

gcc/testsuite/ChangeLog:

	* g++.target/i386/pr110170.C: New test.
	* gcc.target/i386/pr110170.c: New test.