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.