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

libc/calls/now.c

@@ -102,7 +102,7 @@ static long double nowl_vdso(void) {
 long double nowl_setup(void) {
   bool isfast;
   uint64_t ticks;
-  __gettime = __get_clock_gettime(&isfast);
+  __gettime = __clock_gettime_get(&isfast);
   if (isfast) {
     nowl = nowl_vdso;
   } else if (X86_HAVE(INVTSC)) {