RFR: 8282773: Refactor parsing of integer VM options

[Ioi Lam]

Background:

When a VM option is given an integer value (e.g., `-XX:ActiveProcessorCount=123`), we call the `set_numeric_flag` function in arguments.cpp. The old implementation always calls `strtoull()` to get an unsigned 64-bit number, and then tries to cast/truncate the result to the target type, performing sign conversion as needed.

This is cumbersome and buggy, because the target type (such as `size_t`) may have different bit-widths on different platforms. Also, manual conversion of unsigned to sign values can run into corner cases.

The fix:

- Use C++ templates and SFINAE to automatically choose the correct `parse_integer_impl()` function for parsing the input string. The VM should avoid doing cast and sign conversion as much as possible.
- Use a similar technique to write a comprehensive set of test cases to validate the implementation. (This has revealed several failures in the old implementation).

Notes on K/M/G/T suffix handling:

For input like `-XX:ActiveProcessorCount=2048m`, the old implementation checks for overflow with `(n * suffix / suffix) == n`. This works for unsigned types because the [C++ specification](https://en.cppreference.com/w/cpp/language/operator_arithmetic) allows unsigned arithmetic to overflow. However, overflowing a signed integer is UB. Therefore, I wrote a new function `multiply_by_1k()` to check for overflow without potentially undefined behavior. Thanks to @kimbarrett for helping me come up with the solution.

Tests:

tiers 1-2 passed. tiers 3-5 in progress.

-------------

Commit messages:
 - fixed handling of errno
 - add #include <limits> for std::numeric_limits<T>
 - avoid UB in multiply_by_1k(); more clean-up
 - avoid UB operations in k/m/g/t muplication
 - refactored test cases
 - step3
 - step2
 - tmp1

Changes: https://git.openjdk.java.net/jdk/pull/7763/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=7763&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8282773
  Stats: 585 lines in 4 files changed: 380 ins; 155 del; 50 mod
  Patch: https://git.openjdk.java.net/jdk/pull/7763.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/7763/head:pull/7763

PR: https://git.openjdk.java.net/jdk/pull/7763