Make build hermetic without shell scripts

- Fix some minor issues in ar.com
- Have execve() look for `ape` command
- Rewrite NT paths using /c/ rather /??/c:/
- Replace broken GCC symlinks with .sym files
- Rewrite $PATH environment variables on startup
- Make $(APE_NO_MODIFY_SELF) the default bootloader
- Add all build command dependencies to build/bootstrap
- Get the repository mostly building from source on non-Linux

test/libc/release/metal.sh

@@ -10,7 +10,7 @@ if [ "$MODE" = opt ] || [ "$MODE" = optlinux ]; then
   exit
 fi
 
-mkdir -p o/$MODE/test/libc/release/
+$MKDIR o/$MODE/test/libc/release/
 
 # smoke test booting on bare metal and printing data to serial uart
 CMD="o/$MODE/tool/build/blinkenlights.com.dbg -r o/$MODE/examples/hello.com"