conformtest: Correct some stdlib.h expectations for XPG3.

This patch corrects some spurious conformtest stdlib.h expectations
for XPG3 (not based on a full review of the expectations for that
standard, so other issues may remain).

Tested for x86_64 and x86.

	* conform/data/stdlib.h-data (a64l): Do not expect for [XPG3].
	(ecvt): Likewise.
	(fcvt): Likewise.
	(gcvt): Likewise.
	(getsubopt): Likewise.
	(grantpt): Likewise.
	(initstate): Likewise.
	(l64a): Likewise.
	(mktemp): Likewise.
	(mkstemp): Likewise.
	(ptsname): Likewise.
	(random): Likewise.
	(realpath): Likewise.
	(setstate): Likewise.
	(srandom): Likewise.
	(ttyslot): Likewise.
	(unlockpt): Likewise.
	(valloc): Likewise.