* glibc .so files
   - without stage1 c++ code integration it should fail with a better error message
     instead of lld not getting the object file on the linker line for some reason.
   - stage1 C++ code integration
   - ok file
 * support rpaths in ELF linker code
 * build & link against compiler-rt
 * build & link againstn freestanding libc
 * add CLI support for a way to pass extra flags to c source files
 * implement the workaround for using LLVM to detect native CPU features
 * self-host main.cpp
 * capture lld stdout/stderr better
 * musl
 * mingw-w64
 * port the stage1 os.cpp code that raises the open fd limit
 * use global zig-cache dir for crt files
 * `zig translate-c`
 * make sure zig cc works
   - using it as a preprocessor (-E)
   - @breakpoint(); // TODO the first arg is empty string right? skip past that.
   - try building some software
 * MachO LLD linking
 * COFF LLD linking
 * WASM LLD linking
 * implement proper parsing of LLD stderr/stdout and exposing compile errors
 * implement proper parsing of clang stderr/stdout and exposing compile errors
 * implement proper compile errors for failing to build glibc crt files and shared libs
 * self-host link.cpp and building libcs (#4313 and #4314). using the `zig cc` command will set a flag indicating a preference for the llvm backend, which will include linking with LLD. At least for now. If zig's self-hosted linker ever gets on par with the likes of ld and lld, we can make it always be used even for zig cc.
 * improve the stage2 tests to support testing with LLVM extensions enabled
 * multi-thread building C objects
 * support cross compiling stage2 with `zig build`
 * implement emit-h in stage2
 * implement -fno-emit-bin
 * audit the base cache hash
 * implement serialization/deserialization of incremental compilation metadata
 * incremental compilation - implement detection of which source files changed
 * improve the cache hash logic for c objects with respect to extra flags and file parameters
 * LLVM codegen backend: put a sub-arch in the triple in some cases
 * implement an LLVM backend for stage2
 * implement outputting dynamic libraries in self-hosted linker
 * implement outputting static libraries (archive files) in self-hosted linker
 * support linking against object files in self-hosted linker
 * avoid invoking lld when it's just 1 object file (the `zig cc -c` case)
 * `zig fmt --check` should output to stdout not stderr.
 * main.zig: If there was an argsAllocZ we could avoid this allocation
 * improve robustness of response file parsing
 * there are a couple panic("TODO") in clang options parsing
 * std.testing needs improvement to support exposing directory path for its tmp dir (look for "bogus")
 * integrate target features into building assembly code
 * libc_installation.zig: make it look for msvc only if msvc abi is chosen
 * switch the default C ABI for windows to be mingw-w64
 * port windows_sdk.cpp to zig
 * change glibc log errors to normal exposed compile errors
 * update Package to use Compilation.Directory in create()
   - skip LLD caching when bin directory is not in the cache (so we don't put `id.txt` into the cwd)
     (maybe make it an explicit option and have main.zig disable it)
   - make it possible for Package to not openDir and reference already existing resources.
 * rename src/ to src/stage1/
 * rename src-self-hosted/ to src/