macOS: If using Xcode CLT >= 15, add -Wl,-ld_classic in create_sysimg_from_object_file()

[DilumAluthge]

Replaces #935 (closes #935)
Reference #738

---

This is based on #935. All credit goes to @PhilReinhold for providing the fix and @jayscook for opening the original PR (#935).

This PR differs slightly from #935. #935 used a try-catch. This PR uses ignorestatus() to ignore non-zero exit codes from running the $cc --version command, and uses isnothing() to handle the case where the regex does not match. Also, this PR factors out the "detect CLT major version" functionality out into a separate helper function.

Also, this PR now addresses #935 (comment)

We do not add these flags for CLT versions <= 14.

[DilumAluthge]

This PR doesn't yet address #935 (comment), but I'll look into it further.

Okay, #935 (comment) is now addressed by the combination of c9a4b52 and adf5737.

[codecov]

Codecov Report

Attention: Patch coverage is 48.64865% with 19 lines in your changes missing coverage. Please review.

Project coverage is 83.00%. Comparing base (38629b0) to head (f387dbb).
Report is 23 commits behind head on master.

Files with missing lines	Patch %	Lines
src/xcode.jl	43.75%	18 Missing ⚠️
src/PackageCompiler.jl	80.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #972      +/-   ##
==========================================
- Coverage   84.56%   83.00%   -1.57%     
==========================================
  Files           3        4       +1     
  Lines         823      859      +36     
==========================================
+ Hits          696      713      +17     
- Misses        127      146      +19     

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[DilumAluthge]

Okay, #935 (comment) is now addressed by the combination of c9a4b52 and adf5737.

[DilumAluthge]

Specifically, we now run $cc --version, and we use that output to determine whether or not the compiler is the Clang from Xcode.

[DilumAluthge]

It's not entirely clear to me if we still need this PR, because #930 seems to have fixed #738, at least in the macOS CI on this repo.

[jayscook]

Thanks for putting this together @DilumAluthge!

[DilumAluthge]

@jayscook Thank you for putting the original PR together (and thank you to @PhilReinhold for writing the original code).

[DilumAluthge]

@topolarity Could you take a look at this PR, and let me know if it addresses your concerns in #935 (comment) and #935 (comment)?

[topolarity]

Sure thing! Looks like the right direction, but I won't be able to take a close look until Monday

[DilumAluthge]

Sounds good, thanks man!

[DilumAluthge]

@sjkelly I see you also reviewed the original PR (#935), so I've requested your review on this one.