Mark various libm tests with xfail-rounding:ldbl-128ibm.

Mark various libm tests with xfail-rounding:ldbl-128ibm.

This patch marks various libm tests with xfail-rounding:ldbl-128ibm,
where the failures appear to relate to GCC bug 59666 (bad libgcc
handling of directed rounding), so as to allow clean libm-test-ulps
regeneration without needing to edit out large ulps for various
functions manually.

Note that this only deals with the cases problematic for ulps
regeneration.  There are plenty of test failures left that do not
affect ulps regeneration - results that are infinities or NaNs but
should be finite, or vice versa, and missing and spurious exceptions -
which should also be resolved during the release testing period.

Tested for powerpc32 (hard float).

	* math/auto-libm-test-in: Mark various tests with
	xfail-rounding:ldbl-128ibm.
	* math/auto-libm-test-out: Regenerated.