libstdc++: Drop format attribute from snprintf wrapper [PR116969]

libstdc++: Drop format attribute from snprintf wrapper [PR116969]

When __LONG_DOUBLE_IEEE128__ is defined we need to declare a wrapper for
Glibc's 'snprintf' symbol, so we can call the original definition that
works with the IBM128 format of long double. Because we were declaring
the wrapper using __typeof__(__builtin_snprintf) it inherited the
__attribute__((format(printf, 3, 4))) decoration, and then we got a
warning for calling that wrapper with an __ibm128 argument for a %Lf
conversion specifier. The warning is bogus, because the function we're
calling really does want __ibm128 for %Lf, but there's no "printf but
with a different long double format" archetype for the attribute.

In r15-4039-g28911f626864e7 I added a diagnostic pragma to suppress the
warning, but it would be better to just declare the wrapper without the
attribute, and not have to suppress a warning for code that we know is
actually correct.

libstdc++-v3/ChangeLog:

	PR libstdc++/116969
	* include/bits/locale_facets_nonio.tcc (money_put::__do_put):
	Remove diagnostic pragmas.
	(__glibcxx_snprintfibm128): Declare type manually, instead of
	using __typeof__(__builtin_snprintf).