Remove redundant defines for UINT32_C, etc

[khwilliamson]

These are furnished by C99 compilers; no need for us to have them too. The set we did have was incomplete.

What other constants can we remove that are in C99?

B.17 Integer types <stdint.h>
intN_t
uintN_t
int_leastN_t
uint_leastN_t
int_fastN_t
uint_fastN_t
intptr_t
uintptr_t
intmax_t
uintmax_t
INTN_MIN
INTN_MAX
UINTN_MAX
INT_LEASTN_MIN
INT_LEASTN_MAX
UINT_LEASTN_MAX
INT_FASTN_MIN
INT_FASTN_MAX
UINT_FASTN_MAX
INTPTR_MIN
INTPTR_MAX
UINTPTR_MAX
INTMAX_MIN
INTMAX_MAX
UINTMAX_MAX
PTRDIFF_MIN
PTRDIFF_MAX
SIG_ATOMIC_MIN
SIG_ATOMIC_MAX
SIZE_MAX
WCHAR_MIN
WCHAR_MAX
WINT_MIN
WINT_MAX
INTN_C(value)
UINTN_C(value)
INTMAX_C(value)
UINTMAX_C(value)

• This set of changes does not require a perldelta entry.

[khwilliamson]

@tonycoz additions lgtm

[tonycoz]

Unfortunately checking against 2015 was just checking that the stdint.h header exists. VS2015 very much wanted to use the latest SDK I had installed... which it isn't compatible with.