Fix nss/tst-nss-test1.c format warning.

Testing for 32-bit x86 shows up a warning "tst-nss-test1.c:25:3:
warning: format '%ju' expects argument of type 'uintmax_t', but
argument 2 has type 'int' [-Wformat=]".  The argument is a difference
of two pointers, a signed quantity of type ptrdiff_t for which the
right format is %td; this patch makes this test use that format.

Tested for 32-bit x86.

	* nss/tst-nss-test1.c (do_test): Use %td printf format for pointer
	difference, not %ju.
Fix stdio-common/tst-fmemopen.c format warnings.

Testing for 32-bit x86 shows up warnings in
stdio-common/tst-fmemopen.c where off_t values are passed to %zu
printf formats.  Since the values are in messages relating to function
calls where the relevant argument is of type size_t, it seems most
appropriate to cast explicitly to size_t when passing to printf, which
this patch does.

Tested for 32-bit x86.

	* stdio-common/tst-fmemopen.c (do_test): Cast st_size values to
	size_t for %zu format.
Don't use __warn_memset_zero_len for gcc-5.0 or newer

gcc now warns when the arguments to memset may have been accidentally
transposed (i.e. length set to zero instead of the byte), so we don't
need that bit of the code in glibc headers anymore.

Tested on x86_64.  Coe generated by gcc 4.8 is identical with or
without the patch.  I also tested gcc master, which does not result in
any new failures.  It does fail quite a few FORTIFY_SOURCE tests, but
those failures are not due to this patch.
Add missing include of libc-internal.h.
Fix dlfcn/failtestmod.c warning.

This patch fixes a "set but not used" warning from
dlfcn/failtestmod.c.  A variable is used only to store the return
value from dlsym.  As I understand this test, the point is simply to
do a sequence of load / unload operations in a loop, and all that
matters here is that dlsym gets called and returns without crashing,
not what its return value is.  So this patch removes the assignment to
a variable.

Tested for x86_64.

	* dlfcn/failtestmod.c (constr): Do not store result of dlsym in a
	variable.
Fix libio/bug-ungetwc1.c warning.

This patch fixes a warning "variable 'wc' set but not used" in
libio/bug-ungetwc1.c.

The test didn't verify much about the results of the functions it
called.  This patch makes it check the result of getwc (thereby fixing
the warning), check end of file does not arrive too late in the getwc
loop, and check EOF is no longer set after ungetwc.

Tested for x86_64.

	* libio/bug-ungetwc1.c (do_test): Verify results of getwc and
	feof.
Avoid deprecated sigblock in misc/tst-pselect.c.

misc/tst-pselect.c uses the deprecated sigblock interface, resulting
in "tst-pselect.c:42:3: warning: 'sigblock' is deprecated (declared at
../signal/signal.h:189) [-Wdeprecated-declarations]".  The choice of
sigblock rather than sigprocmask has nothing to do with what this test
is testing, so this patch changes it to use sigprocmask to avoid the
warning.

Tested for x86_64.

	* misc/tst-pselect.c (do_test): Use sigprocmask instead of
	sigblock.
Recognize recent x86 CPUs in string.h