Make the root Makefile macOS compatible

[iamluc]

Description

Make make install works out of the box on MacOS, like on Linux.

Reviewer checklist

• Test coverage seems ok.
• Appropriate labels assigned.

[bwoebi]

We can't rely on rustc being in PATH (that's also why we do have e.g. AC_CHECK_TOOL(DDTRACE_CARGO, cargo, [:]) for cargo).

If this is specifically a problem with our Makefile, it must be an interaction with the Makefile. After all, it works when run isolated. I'd rather fix the Makefile than changing config.m4 here.

[iamluc]

For the context, it seems the host & target settings require a non-empty string for non-Linux platform.
It works on macOS when run isolated because the cc crate is locked to version 1.0.83 where this restriction does not seem to exist.
The error occurs with our Makefile because the latest cc crate version is used instead (1.0.92 at the time of writing).

But to avoid the dependency on the rustc binary, I moved the detection to the sidecar mockgen code directly.
WDYT?

[pr-commenter]

Benchmarks

Benchmark execution time: 2024-04-15 07:36:47

Comparing candidate commit 54775b9 in PR branch lv/macos-makefile-compatibility with baseline commit e721e34 in branch master.

Found 0 performance improvements and 4 performance regressions! Performance is the same for 174 metrics, 0 unstable metrics.

scenario:PDOBench/benchPDOBaseline-opcache

• 🟥 execution_time [+13.076µs; +15.805µs] or [+7.520%; +9.089%]

scenario:PDOBench/benchPDOOverhead-opcache

• 🟥 execution_time [+14.781µs; +15.883µs] or [+8.551%; +9.189%]

scenario:PDOBench/benchPDOOverheadWithDBM-opcache

• 🟥 execution_time [+15.674µs; +18.078µs] or [+9.034%; +10.421%]

scenario:TraceSerializationBench/benchSerializeTrace

• 🟥 execution_time [+11.887µs; +16.113µs] or [+6.571%; +8.907%]

[codecov-commenter]

Codecov Report

Merging #2614 (54775b9) into master (e721e34) will increase coverage by 1.57%.
The diff coverage is n/a.

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #2614      +/-   ##
============================================
+ Coverage     77.64%   79.21%   +1.57%     
  Complexity     2226     2226              
============================================
  Files           226      200      -26     
  Lines         25942    21942    -4000     
  Branches        986        0     -986     
============================================
- Hits          20142    17382    -2760     
+ Misses         5274     4560     -714     
+ Partials        526        0     -526     

Flag	Coverage Δ
appsec-extension	?
tracer-extension	78.54% <ø> (ø)
tracer-php	80.16% <ø> (ø)

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see 26 files with indirect coverage changes

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[bwoebi]

Okay, looks good then :-)