conformtest: Correct ftw.h expectations for XPG3, XPG4.

This patch corrects various conformtest expectations in ftw.h for XPG3
and XPG4.

Tested for x86_64 and x86.

	* conform/data/ftw.h-data (struct FTW): Do not expect for [XPG3].
	(FTW_DP): Do not expect for [XPG3 || XPG4].
	(FTW_SL): Do not expect for [XPG3].
	(FTW_SLN): Likewise.
	(FTW_PHYS): Likewise.
	(FTW_MOUNT): Likewise.
	(FTW_DEPTH): Likewise.
	(FTW_CHDIR): Likewise.
	(nftw): Likewise.
	* conform/Makefile (test-xfail-XPG3/ftw.h/conform): Remove
	variable.