More cancellation handling fixups.
* sysdeps/unix/sysv/linux/not-cancel.h: Add waitpid_not_cancel.
* sysdeps/generic/not-cancel.h: Likewise.
* catgets/open_catalog.c: Use not-cancelable syscalls.
* time/Makefile (CFLAGS-getdate.c): Add -fexceptions.
* sysdeps/unix/sysv/linux/llseek.c: Must not be cancelable.
* sysdeps/unix/syscalls.list: Don't mark lseek as cancelable.
* dlfcn/dlfcn.h: Mark dlopen with __THROW again.
* io/fcntl.h: Don't mark posix_fallocate with __THROW.
* libio/fileops.c: Use not-cancelable syscalls for fclose.
* libio/iopopen.c: Use no-cancelable syscalls.
* libio/stdio.h: Mark popen and pclose with __THROW again.
* misc/Makefile (CFLAGS-syslog.c): Add -fexceptions.
* misc/syslog.c: Fix locking and cancellation cleanup handling.
* posix/unistd.h: Mark ttyname and ttyname_r again with __THROW.
* stdio-common/Makefile (CFLAGS-tmpfile.c, CFLAGS-tmpfile64.c,
CFLAGS-tempname.c): Add -fexceptions.
* stdlib/Makefile (CFLAGS-mkstemp.c): Add -fexceptions.
* string/string.h: Mark strerror and strerror_r with _THROW again.
* sysdeps/generic/unwind.inc: New file. Copied from gcc.
* sysdeps/generic/unwind-dw2.c: Update from gcc version. Remove
#ifs since we now need all the code compiled.
* sysdeps/posix/spawni.c: Use close_not_cancel instead of close.
* sysdeps/unix/closedir.c: Use not-cancelable syscalls.
* sysdeps/unix/opendir.c: Likewise.