Use go:linkname instead of asm jmp.

[fumiama]

• go:linkname is equivalent to asm jmp and simpler.
• No need to add a new stub file on each new arch.
• This may also fix compiling error of gccgo such as ARM support, for EdgeX Foundry and gollvm #12 fix build with gccgo #14.

[fumiama]

Hi @remyoudompheng , as you can see, there is no need to use plenty of stub files for all architectures and just one file using go:linkname can do that. Hope you can merge this pr and revert previously merged #19 . Thanks!

[remyoudompheng]

This is definitely better indeed.