libstdc++: Stop using _GLIBCXX_USE_C99_STDINT_TR1 in <cstdint>

The _GLIBCXX_USE_C99_STDINT_TR1 macro (and the comments about it in
acinclude.m4 and config.h) are misleading when it is also used for
<stdint>, not only <tr1/stdint>. It is also wrong, because the
configure checks for TR1 use -std=c++98 and a target might define
uint32_t etc. for C++11 but not for C++98.

Add a separate configure check for the <stdint.h> types using -std=c++11
for the checks. Use the result of that separate check in <cstdint> and
most other places that still depend on the macro (many uses of that
macro have been removed already). The remaining uses of the STDINT_TR1
macro are really for TR1, or are in the src/c++11/compatibility-*.cc
files, where we don't want/need to change the condition they depend on
(if those symbols were only exported when <stdint.h> types were
available for -std=c++98, then that's the condition we should continue
to use for whether to export the compat symbols now).

Make similar changes for the related _GLIBCXX_USE_C99_INTTYPES_TR1 and
_GLIBCXX_USE_C99_INTTYPES_WCHAR_T_TR1 macros, adding new macros for
non-TR1 uses.

libstdc++-v3/ChangeLog:

	* acinclude.m4 (GLIBCXX_USE_C99): Check for <stdint.h> types in
	C++11 mode and define _GLIBCXX_USE_C99_STDINT. Check for
	<inttypes.h> features in C++11 mode and define
	_GLIBCXX_USE_C99_INTTYPES and _GLIBCXX_USE_C99_INTTYPES_WCHAR_T.
	* config.h.in: Regenerate.
	* configure: Regenerate.
	* doc/doxygen/user.cfg.in (PREDEFINED): Add new macros.
	* include/bits/chrono.h: Check _GLIBCXX_USE_C99_STDINT instead
	of _GLIBCXX_USE_C99_STDINT_TR1.
	* include/c_compatibility/inttypes.h: Check
	_GLIBCXX_USE_C99_INTTYPES and _GLIBCXX_USE_C99_INTTYPES_WCHAR_T
	instead of _GLIBCXX_USE_C99_INTTYPES_TR1 and
	_GLIBCXX_USE_C99_INTTYPES_WCHAR_T_TR1.
	* include/c_compatibility/stdatomic.h: Check
	_GLIBCXX_USE_C99_STDINT instead of _GLIBCXX_USE_C99_STDINT_TR1.
	* include/c_compatibility/stdint.h: Likewise.
	* include/c_global/cinttypes: Check _GLIBCXX_USE_C99_INTTYPES
	and _GLIBCXX_USE_C99_INTTYPES_WCHAR_T instead of
	_GLIBCXX_USE_C99_INTTYPES_TR1 and
	_GLIBCXX_USE_C99_INTTYPES_WCHAR_T_TR1.
	* include/c_global/cstdint: Check _GLIBCXX_USE_C99_STDINT
	instead of _GLIBCXX_USE_C99_STDINT_TR1.
	* include/std/atomic: Likewise.
	* src/c++11/cow-stdexcept.cc: Likewise.
	* testsuite/29_atomics/headers/stdatomic.h/c_compat.cc:
	Likewise.
	* testsuite/lib/libstdc++.exp (check_v3_target_cstdint):
	Likewise.