We use `stdint.h` unconditionally in all places except one. These uses
are imposed by external dependencies / features. nghttp2, quic, wolfSSL
and `HAVE_MACH_ABSOLUTE_TIME` do require this C99 header. It means that
any of these features make curl require a C99 compiler. (In case of
MSVC, this means Visual Studio 2010 or newer.)
This patch changes the single use of `stdint.h` guarded by
`HAVE_STDINT_H` to use `stdint.h` unconditionally. Also stop using
`inttypes.h` as an alternative there. `HAVE_INTTYPES_H` wasn't used
anywhere else, allowing to delete this feature check as well.
Closes#12275
60359ad504