math: fix failing test on FreeBSD with gcc 12.2.0 (and -ffast-math)

[spytheman]

Both invocations below pass now on FreeBSD 13.0-RELEASE-p13:
v -fast-math -cc gcc vlib/math/math_test.v
and
v -cc gcc vlib/math/math_test.v

🤖 Generated by Copilot at 6d1f811

This pull request enhances the vlib/math module by improving the test coverage and reliability, fixing the floating-point comparison and NaN detection, and adding some debugging prints. These changes are mainly related to the -fast-math flag and its effects on the math functions.

🤖 Generated by Copilot at 6d1f811

• Add a condition to is_nan to handle quiet NaNs with fast math (link)
• Skip or modify some tests in math_test.v that may fail with fast math due to different behavior of acos, atan2, sign, and exp functions (link, link, link, link)
• Remove a redundant condition in test_round that was skipping assertions involving zero (link)
• Improve the alike function in math.v to use a more robust comparison of floating-point numbers, ignoring the last two bits of the binary representation (link)
• Add some print statements in round and alike for debugging purposes, which should be removed before merging (link, link)