Bug 23561: Fix NSIS builds for Windows 64

This commit adds support for building the 64-bit version of NSIS, and
also bumps the version to 3.03. Doing this enables us to build MAR files
in a 64-bit container for the 64-bit version of Tor Browser; see bug
26363 and bug 24477.

The pe_checksum_fix.py doesn't work in a 64-bit container with the
bundled python-pefile version so we build its latest version to fix this
issue. This change is borrowed from commit bb32ec91 and updates
python-pefile to 2017.11.5.

The Debian package and the patches are no longer required as all changes
were merged upstream in 3.01-1. (See the nsis changelog in Debian.)