fix arraymodule for overflow checking

[bdaf8532-ded6-4d4c-9bb3-51fd76040dc1]

BPO	400506
Nosy	@freddrake
Files	None: None

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GitHub fields: ```python assignee = 'https://github.com/freddrake' closed_at = created_at = labels = [] title = 'fix arraymodule for overflow checking' updated_at = user = 'https://bugs.python.org/tmick' ``` bugs.python.org fields: ```python activity = actor = 'tmick' assignee = 'fdrake' closed = True closed_date = None closer = None components = ['None'] creation = creator = 'tmick' dependencies = [] files = ['2437'] hgrepos = [] issue_num = 400506 keywords = ['patch'] message_count = 3.0 messages = ['32689', '32690', '32691'] nosy_count = 2.0 nosy_names = ['fdrake', 'tmick'] pr_nums = [] priority = 'normal' resolution = None stage = None status = 'closed' superseder = None type = None url = 'https://bugs.python.org/issue400506' versions = [] ```

[bdaf8532-ded6-4d4c-9bb3-51fd76040dc1]

[bdaf8532-ded6-4d4c-9bb3-51fd76040dc1]

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[bdaf8532-ded6-4d4c-9bb3-51fd76040dc1]

The cause: Relatively recent (last month) patches to getargs.c added overflow checking to the PyArg_Parse*() integral formatters thereby restricting 'b' to unsigned char value and 'h','i', and 'l' to signed integral values (i.e. if the incoming value is outside of the specified bounds you get an OverflowError, previous it silently overflowed).

The problem: This broke the array module (as Fredrik pointed out) because *its formatters relied on the loose allowance of signed and unsigned ranges being able to pass through PyArg_Parse()'s formatters.

The fix: This patch fixes the array module to work with the more strict bounds checking now in PyArg_Parse*().

How: If the type signature of a formatter in the arraymodule exactly matches one in PyArg_Parse(), then use that directly. If there is no equivalent type signature in PyArg_Parse() (e.g. there is no unsigned int formatter in PyArg_Parse*()), then use the next one up and do some extra bounds checking in the array module.

Testing: test_array.py was also extended to check that one can set the full range of values for each of the integral signed and unsigned array types.