Zig upstream tracking issues

[kassane]

• Remove usingnamespace ziglang/zig#20663
• move @cImport to the build system ziglang/zig#20630
• Improve LibC interface in build.zig ziglang/zig#20327
• zig cc, zig c++, zig translate-c and other subcommands without a clang/llvm dependency in the compiler binary ziglang/zig#20875
• Xtensa Support ziglang/zig#5467
  • Tracking Issue for merging to upstream (LLVM-57) espressif/llvm-project#4