(issue54) Implement a privilege drop to execute the program after installation. This commit is extremly ugly as I accidentally worked in a working tree that was partially merged with default. To review the real change please check the commit that will merge this branch into default.

When linking against a shared nss build the nss installation program
has the following NSS run time dependencies:

 - nssckbi.dll
 - smime3.dll
 - nss3.dll
 - nssdbm3.dll
 - softokn3.dll
 - sqlite3.dll
 - freebl3.dll
 - nssutil3.dll
 - libplc4.dll
 - libplds4.dll
 - libnspr4.dll