LLVM 18.1.6

[h-vetinari]

Blockers for merging this PR and thus enabling the compilers in conda-forge (indentation denotes dependency):

• llvmdev v18.1.6 llvmdev-feedstock#264
  • clangdev v18.1.6 clangdev-feedstock#285
    • Build for LLVM 18 cctools-and-ld64-feedstock#65 (only needs major version)
    • compiler-rt v18.1.6 compiler-rt-feedstock#107
      • openmp v18.1.6 openmp-feedstock#124
    • libcxx v18.1.4 libcxx-feedstock#144 (still using libcxx 17 here for now)
  • lld v18.1.6 lld-feedstock#92

Related feedstocks for LLVM 18.1.6 support more generally:

• https://github.com/conda-forge/clang-win-activation-feedstock (windows side of this PR; needs this PR)
• Add clang 18 ctng-compiler-activation-feedstock#104 (only needs major version)
• flang v18.1.6 flang-feedstock#50 (needs mlir, openmp, compiler-rt)
• Add testing against clang 17 & 18 libcxx-testing-feedstock#6 (only needs major version)
• lldb v18.1.6 lldb-feedstock#67 (needs this PR)
• mlir v18.1.6 mlir-feedstock#70 (needs llvmdev)
• mlir-python-bindings v18.1.6 mlir-python-bindings-feedstock#27 (needs llvmdev & mlir)

[conda-forge-webservices]

Hi! This is the friendly automated conda-forge-linting service.

I just wanted to let you know that I linted all conda-recipes in your PR (recipe) and found it was in an excellent condition.

[github-actions]

Hi! This is the friendly conda-forge automerge bot!

I considered the following status checks when analyzing this PR:

• linter: passed
• azure: passed

Thus the PR was passing and merged! Have a great day!