haiku: get cmake bootstrap working

[jacobly0]

~> pkgman install zlib_devel cmake ninja mimalloc
~/llvm> cmake -GNinja -Sllvm -Bbuild -DCMAKE_BUILD_TYPE=Release -DCMAKE_INSTALL_PREFIX=$HOME/llvm/install -DLLVM_ENABLE_PROJECTS="clang;lld" -DLLVM_BUILD_LLVM_DYLIB=ON
~/llvm> cmake --build build
~/llvm> cmake --install build
~/zig> cmake -GNinja -S. -Bbuild -DCMAKE_PREFIX_PATH=$HOME/llvm/install -DZIG_NO_LIB=ON
~/zig> LD_PRELOAD=/system/lib/libmimalloc.so.2 cmake --build build
~/zig> cmake --install build

• The llvm dylib option is to work around there not being a static stdc++ installed.
• The mimalloc preload is to work around bugs in the system malloc impl.
• Unfortunately, this still produces a final executable with 3 invalid relocations, for which I'm currently blaming lld (both because lld is emitting the incorrect relocation and because the source code being linked to use the wrong relocation is also the lld source code). fixed
• -fno-lld does not work, probably the same issue as the previous fixed one. Partially fixed, hello world works, but still a linking issues with tests.
• Zig threadlocal variables do not work, defaulting to single threaded for now.

Closes #19485