Generated Makefile fails on OpenBSD 5.3

While trying to install node-sqlite3 via `npm install sqlite3` I got this error:
```
  COPY Release/sqlite3.a
cp: unknown option -- a
usage: cp [-fip] [-R [-H | -L | -P]]
       cp [-fip] [-R [-H | -L | -P]]
gmake: *** [Release/sqlite3.a] Error 1
```

Turns out the archive flag isn't available in the cp binary on OpenBSD, but it looks like it's just a shortcut for -pPR.