Remove __libc_creat function name.

glibc has lots of __libc_* function names that no longer serve any
purpose (are not used for any calls or exported at a public symbol
version).  This patch removes __libc_creat.  It has the effect of
creat becoming a strong symbol instead of a weak symbol in various
cases, but that's fine; in shared libraries it doesn't matter at all,
while for static linking the only other symbol sometimes defined in
the same object is creat64, and whenever creat64 is a reserved name so
is creat.

Other such cases of unnecessary __libc_* symbols are expected to be
dealt with in separate patches over time.

Tested for x86_64 (testsuite, and that the disassembly of installed
shared libraries is unchanged by the patch).

	* include/fcntl.h (__libc_creat): Remove declaration.
	* io/creat.c (__libc_creat): Rename to creat.
	(creat): Do not define as alias.
	* sysdeps/unix/sysv/linux/alpha/creat.c (creat64): Define as alias
	of creat instead of __libc_creat.
	* sysdeps/unix/sysv/linux/generic/creat.c (__libc_creat): Rename
	to creat.
	(creat): Do not define as alias.
	[__WORDSIZE == 64] (creat64): Define as alias of creat instead of
	__libc_creat.
	* sysdeps/unix/sysv/linux/syscalls.list (creat): Do not define
	__libc_creat name.
	* sysdeps/unix/sysv/linux/wordsize-64/syscalls.list (creat):
	Likewise.

sysdeps/unix/sysv/linux/alpha/creat.c

@@ -5,4 +5,4 @@
    could have overridden that with a create64.c, but we might as well do
    the right thing and set up creat64 as an alias.  */
 #include <io/creat.c>
-weak_alias(__libc_creat, creat64)
+weak_alias(creat, creat64)