Manual type promotion for arcsine distribution

[JacobHass8]

This tries to rewrite #1299 in a more human readable way. See #1294 for the same issue with the logistic distribution.

[JacobHass8]

@mborland what do you think of this version? I made a number of actual changes to the code that I'd like to get your opinion on. I left comments below.

On an unrelated note, I wasn't able to get b2 to run test_arcsine. I was getting more errors than I could count. Is it set up to run or is it skipped for some reason?

[mborland]

On an unrelated note, I wasn't able to get b2 to run test_arcsine. I was getting more errors than I could count. Is it set up to run or is it skipped for some reason?

It is setup to run, and I just tried it on head and the test ran fine. What's the issue? You can try pch=off if you're getting a bunch of errors propagating from the usage of pre-compiled headers.

[mborland]

I do think this approach looks better. Thanks!

[codecov]

Codecov Report

❌ Patch coverage is 98.57143% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 95.35%. Comparing base (e6fb7d3) to head (8e919f2).

Files with missing lines	Patch %	Lines
include/boost/math/distributions/arcsine.hpp	98.38%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #1373      +/-   ##
===========================================
+ Coverage    95.34%   95.35%   +0.01%     
===========================================
  Files          825      825              
  Lines        68160    68175      +15     
===========================================
+ Hits         64986    65010      +24     
+ Misses        3174     3165       -9     

Files with missing lines	Coverage Δ
include/boost/math/policies/policy.hpp	95.83% <ø> (ø)
test/test_arcsine.cpp	99.18% <100.00%> (+0.02%)	⬆️
include/boost/math/distributions/arcsine.hpp	96.11% <98.38%> (+4.78%)	⬆️

... and 1 file with indirect coverage changes

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[JacobHass8]

On an unrelated note, I wasn't able to get b2 to run test_arcsine. I was getting more errors than I could count. Is it set up to run or is it skipped for some reason?

It is setup to run, and I just tried it on head and the test ran fine. What's the issue? You can try pch=off if you're getting a bunch of errors propagating from the usage of pre-compiled headers.

There were just a ton of errors in my code. I missed a couple of closing brackets which caused a large amount of errors.