Native libraries can depend on architecture, not just OS

[tal-m]

Currently, support for different native libraries on different operating systems relies on having a different manifest sections for each OS. However, native libraries also differ according to architecture; for example, Linux has both 32-bit and 64-bit architectures and native libraries for one generally don't work on the other.

Capsule should add support for manifest sections that depend on the system architecture, not just the OS name.