compiler/natives/src/runtime: Add stubs for getcallerpc, findfunc, funcname.
compiler/natives/src/runtime: Add stubs for getcallerpc, findfunc, funcname.

These are used by the new panicwrap implementation. panicwrap wasn't
implemented previously either, so this is not a regression.

Related to https://github.com/golang/go/commit/354fa9a84f7b88fe6b9ebf578e6671c2b511a402.

Fixes:

	runtime/error.go:134:8: undeclared name: getcallerpc
	runtime/error.go:135:10: undeclared name: funcname
	runtime/error.go:135:19: undeclared name: findfunc

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