poc: Add disassemblers for 32- and 64-bit ARM and 64-bit PowerPC

[mewmew]

This is a bite-size issue.

Given that the x/arch repo has implemented disassemblers for 32- and 64-bit ARM and 64-bit PowerPC, it should be fairly straightforward to add support for these within Pippi.

• 32-bit ARM: https://godoc.org/golang.org/x/arch/arm/armasm
• 64-bit ARM: https://godoc.org/golang.org/x/arch/arm64/arm64asm
• 64-bit PowerPC: https://godoc.org/golang.org/x/arch/ppc64/ppc64asm

Reference PR for adding new disassemblers to Pippi: https://github.com/lapsang-boys/pippi/pull/37

Although related, a separate issue would be to add the correct machine architecture enums for ELF and PE binaries. These would be added to the bin.Arch enum, and the mapping would have to be made in the bin/pe and bin/elf packages.

[karlek]

https://github.com/decomp/exp/pull/5

[karlek]

32-bit PowerPC is a want to have feature (as you probably already know) https://github.com/golang/go/issues/22885

[mewmew]

decomp/exp#5

Merged.

[barracuda156]

Indeed, powerpc-apple-darwin (ppc32) will be very much welcomed.