Assembly seems to be broken on riscv

[TethysSvensson]

I've tried using the asm tool for riscv32 and riscv64 and it doesn't seem to work correctly.

Example:

$ asm -c riscv32 'nop'
[!] Could not find system include headers for riscv32-linux
0100
$ asm -c riscv32 'addi x0, x0, 0'
[!] Could not find system include headers for riscv32-linux
0100
$ asm -c riscv32 'addi x0, x0, 1'
[!] Could not find system include headers for riscv32-linux
13001000
$ asm -c riscv64 'nop'
[!] Could not find system include headers for riscv64-linux
0100
$ asm -c riscv64 'addi x0, x0, 0'
[!] Could not find system include headers for riscv64-linux
0100
$ asm -c riscv64 'addi x0, x0, 1'
[!] Could not find system include headers for riscv64-linux
13001000

Instructions in riscv cannot be only two bytes long.

[Arusekk]

See #2419

[TethysSvensson]

My bad, it seems like I don't know riscv very well at all.

Still, I don't think asm produce assembly that only works on processors with the C extension, unless explicitly enabled.