Combine __USE_BSD and __USE_SVID into __USE_MISC.

Combine __USE_BSD and __USE_SVID into __USE_MISC.

This patch cleans up following the obsoletion of _BSD_SOURCE and
_SVID_SOURCE by combining __USE_BSD and __USE_SVID into __USE_MISC.

The only non-mechanical part of this patch is the changes to
features.h; everything else is simple substitution of __USE_MISC for
the old macros.  Thus, this patch leaves obviously redundant
conditionals such as "defined __USE_MISC || defined __USE_MISC", and
does not update #endif comments where they referred to BSD or SVID in
words instead of the literal macro name.  This is intended to
facilitate patch review by separating the less mechanical changes from
these purely mechanical changes into a separate patch.  (I do intend
to integrate all the changes from
<https://sourceware.org/ml/libc-alpha/2013-12/msg00226.html>, which I
believe includes all the trailing comment updates, in subsequent
patches.)

Tested x86_64.

	* include/features.h (__USE_BSD): Remove macro definitions.
	(__USE_SVID): Likewise.
	(_BSD_SOURCE): Likewise.
	(_SVID_SOURCE): Likewise.
	[!defined _BSD_SOURCE && !defined _SVID_SOURCE]: Remove condition
	from definition of _DEFAULT_SOURCE.
	[_BSD_SOURCE || _SVID_SOURCE]: Change condition to
	[_DEFAULT_SOURCE].
	* bits/fcntl.h [__USE_BSD]: Change condition to [__USE_MISC].
	* bits/mman.h [__USE_BSD]: Likewise.
	* bits/termios.h [__USE_BSD]: Likewise.
	* bits/waitstatus.h [__USE_BSD]: Likewise.
	* ctype/ctype.h [__USE_SVID]: Likewise.
	* dirent/dirent.h [__USE_BSD]: Likewise.
	* grp/grp.h [__USE_SVID]: Likewise.
	[__USE_BSD]: Likewise.
	* inet/netinet/igmp.h [__USE_BSD]: Likewise.
	* io/fcntl.h [__USE_BSD]: Likewise.
	* io/ftw.h [__USE_BSD]: Likewise.
	* io/sys/stat.h [__USE_BSD]: Likewise.
	* libio/bits/stdio-ldbl.h [__USE_BSD]: Likewise.
	* libio/bits/stdio2.h [__USE_BSD]: Likewise.
	* libio/stdio.h [__USE_SVID]: Likewise.
	[__USE_BSD]: Likewise.
	* math/math.h [__USE_SVID]: Likewise.
	[__USE_BSD]: Likewise.
	* misc/bits/syslog-ldbl.h [__USE_BSD]: Likewise.
	* misc/bits/syslog.h [__USE_BSD]: Likewise.
	* misc/search.h [__USE_SVID]: Likewise.
	* misc/sys/mman.h [__USE_BSD]: Likewise.
	* misc/sys/syslog.h [__USE_BSD]: Likewise.
	* misc/sys/uio.h [__USE_BSD]: Likewise.
	* posix/bits/unistd.h [__USE_BSD]: Likewise.
	* posix/glob.h [__USE_BSD]: Likewise.
	* posix/regex.h [__USE_BSD]: Likewise.
	* posix/sys/types.h [__USE_BSD]: Likewise.
	[__USE_SVID]: Likewise.
	* posix/sys/utsname.h [__USE_SVID]: Likewise.
	* posix/sys/wait.h [__USE_BSD]: Likewise.
	[__USE_SVID]: Likewise.
	* posix/unistd.h [__USE_BSD]: Likewise.
	[__USE_SVID]: Likewise.
	* pwd/pwd.h [__USE_SVID]: Likewise.
	* resolv/netdb.h [__USE_BSD]: Likewise.
	* setjmp/setjmp.h [__USE_BSD]: Likewise.
	* signal/signal.h [__USE_BSD]: Likewise.
	[__USE_SVID]: Likewise.
	* socket/sys/socket.h [__USE_BSD]: Likewise.
	* stdlib/fmtmsg.h [__USE_SVID]: Likewise.
	* stdlib/stdlib.h [__USE_BSD]: Likewise.
	[__USE_SVID]: Likewise.
	* string/bits/string2.h [__USE_BSD]: Likewise.
	[__USE_SVID]: Likewise.
	* string/bits/string3.h [__USE_BSD]: Likewise.
	* string/endian.h [__USE_BSD]: Likewise.
	* string/string.h [__USE_SVID]: Likewise.
	[__USE_BSD]: Likewise.
	* string/strings.h [__USE_BSD]: Likewise.
	* sysdeps/generic/netinet/ip.h [__USE_BSD]: Likewise.
	* sysdeps/gnu/netinet/ip_icmp.h [__USE_BSD]: Likewise.
	* sysdeps/mach/hurd/bits/fcntl.h [__USE_BSD]: Likewise.
	* sysdeps/mach/hurd/bits/stat.h [__USE_BSD]: Likewise.
	* sysdeps/unix/sysv/linux/alpha/bits/mman.h [__USE_BSD]: Likewise.
	* sysdeps/unix/sysv/linux/alpha/bits/termios.h [__USE_BSD]:
	Likewise.
	* sysdeps/unix/sysv/linux/bits/fcntl-linux.h [__USE_BSD]:
	Likewise.
	* sysdeps/unix/sysv/linux/bits/mman-linux.h [__USE_BSD]: Likewise.
	* sysdeps/unix/sysv/linux/bits/sys_errlist.h [__USE_BSD]:
	Likewise.
	* sysdeps/unix/sysv/linux/bits/termios.h [__USE_BSD]: Likewise.
	* sysdeps/unix/sysv/linux/mips/bits/termios.h [__USE_BSD]:
	Likewise.
	* sysdeps/unix/sysv/linux/netinet/if_ether.h [__USE_BSD]:
	Likewise.
	* sysdeps/unix/sysv/linux/netinet/if_fddi.h [__USE_BSD]: Likewise.
	* sysdeps/unix/sysv/linux/netinet/if_tr.h [__USE_BSD]: Likewise.
	* sysdeps/unix/sysv/linux/powerpc/bits/termios.h [__USE_BSD]:
	Likewise.
	* sysdeps/unix/sysv/linux/sparc/bits/termios.h [__USE_BSD]:
	Likewise.
	* sysdeps/x86/bits/string.h [__USE_BSD]: Likewise.
	* sysvipc/sys/ipc.h [__USE_SVID]: Likewise.
	* termios/termios.h [__USE_BSD]: Likewise.
	* time/sys/time.h [__USE_BSD]: Likewise.
	* time/time.h [__USE_BSD]: Likewise.
	[__USE_SVID]: Likewise.

	* sysdeps/unix/sysv/linux/hppa/bits/mman.h [__USE_BSD]: Change
	condition to [__USE_MISC].