[WIP] Explicitly specify target for Darwin Intel crystal build

[miry]

By default uses the target of the system where the script is executed. If run darwin build on MacOS M1 laptop, it generates 2 arm binaries. And command lito returns error that both files have same arch.

Reproduction of the problem:

$ llvm-config --host-target
arm64-apple-darwin23.0.0

$ make crystal stats=true release=true
Using /usr/local/bin/llvm-config [version= 15.0.7]
CRYSTAL_CONFIG_BUILD_COMMIT="1f592eca6" CRYSTAL_CONFIG_PATH='$ORIGIN/../share/crystal/src' SOURCE_DATE_EPOCH="1699639716"  CRYSTAL_CONFIG_LIBRARY_PATH= ./bin/crystal build --no-debug -D strict_multi_assign ....

$ file .../crystal/embedded/bin/crystal
.../crystal/embedded/bin/crystal: Mach-O 64-bit executable arm64

Problems

Currently I found that make crystal target=x86_64-apple-darwin release=true from crystal repo is not working for me. Looking for way to build dependencies in correct arch.

Relies on changes from #267 and #266