Don’t conditionalize declarations of ldiv_t, lldiv_t, __gwchar_t.

Don’t conditionalize declarations of ldiv_t, lldiv_t, __gwchar_t.

The declarations of ldiv_t, lldiv_t, and __gwchar_t are all wrapped in
__foo_t_defined conditionals, despite there being only one header in
glibc that declares them.  I checked codesearch.debian.net and only
found one other program that refers to the __foo_t_defined
conditionals: u-boot provides its own definition of ldiv_t if
__ldiv_t_defined is not defined by stdlib.h.  I conclude that the
conditionals are not necessary, but the definitions of
__ldiv_t_defined and __lldiv_t_defined should be preserved.

	* stdlib/inttypes.h: Unconditionally define __gwchar_t.
        Don’t define ____gwchar_t_defined.
        * stdlib/stdlib.h: Unconditionally define ldiv_t.
        Condition lldiv_t only on __USE_ISOC99.