nptl: Add missing cancellation flags on lockf

It also removes CFLAGS-lockf.c duplicate rule.  It fixes
nptl/tst-cancelx16 on mips64-linux-gnu.

io/Makefile

@@ -93,7 +93,8 @@ CFLAGS-fcntl.c += -fexceptions -fasynchronous-unwind-tables
 CFLAGS-fcntl64.c += -fexceptions -fasynchronous-unwind-tables
 CFLAGS-poll.c += -fexceptions -fasynchronous-unwind-tables
 CFLAGS-ppoll.c += -fexceptions -fasynchronous-unwind-tables
-CFLAGS-lockf.c += -fexceptions
+CFLAGS-lockf.c += -fexceptions -fasynchronous-unwind-tables
+CFLAGS-lockf64.c += -fexceptions -fasynchronous-unwind-tables
 CFLAGS-statfs.c += -fexceptions
 CFLAGS-fstatfs.c += -fexceptions
 CFLAGS-statvfs.c += -fexceptions
@@ -102,7 +103,6 @@ CFLAGS-fts.c += -Wno-uninitialized $(uses-callbacks) -fexceptions
 CFLAGS-fts64.c += -Wno-uninitialized $(uses-callbacks) -fexceptions
 CFLAGS-ftw.c += $(uses-callbacks) -fexceptions
 CFLAGS-ftw64.c += $(uses-callbacks) -fexceptions
-CFLAGS-lockf.c += -fexceptions
 CFLAGS-posix_fallocate.c += -fexceptions
 CFLAGS-posix_fallocate64.c += -fexceptions
 CFLAGS-fallocate.c += -fexceptions