This takes a bit longer since the interpreted part has to do more work
but it saves a round trip through the compiler by allowing `zig2 build`
to be the final step. 1-2-3, done.
For me this is currently failing due to compilation errors generated by
GCC when compiling zig2.c but in theory if those are fixed, it should
work!
* synchronize zig1.c from zig-wasi external project
* change the way argv works to avoid absolute paths
* autodetect isatty
* compiler_rt: disable some functions when object format is C
* add missing flag from config.zig.in
The next problem is that compiling compiler_rt.c with gcc gives
"conflicting types" errors for `__eqhf2` and friends.
