Move riscv64 crt0 to objcopy

[gmbr3]

gnu-efi should move the crt0 for riscv64 to the objcopy type instead of the 'manual symbols' type as we now have efi-app-riscv64.
We should keep the original and rename it and allow detection of what is the default to prevent mix-ups like ARM64.

Relates to rhboot/shim#641

[ncroxon]

Agreed.

[jmontleon]

@gmbr3 It looks like this may still be a work in progress, based on additional commits since I tried, but I wanted to give some feedback that I was able to use it to build rhboot/shim and boot both a VisionFive 2 and a libvirt VM into Fedora 40 using your work along with the linked PR.

[gmbr3]

@gmbr3 It looks like this may still be a work in progress, based on additional commits since I tried, but I wanted to give some feedback that I was able to use it to build rhboot/shim and boot both a VisionFive 2 and a libvirt VM into Fedora 40 using your work along with the linked PR.

Thanks for your positive feedback
Technically WIP until I get everything I want included done but glad the RISCV64 part works