runtime: remove unused file func.go

This was used in the past, but we don't use it anymore.

src/runtime/func.go

@@ -1,28 +0,0 @@
-package runtime
-
-// This file implements some data types that may be useful for some
-// implementations of func values.
-
-import (
-	"unsafe"
-)
-
-// funcValue is the underlying type of func values, depending on which func
-// value representation was used.
-type funcValue struct {
-	context unsafe.Pointer // function context, for closures and bound methods
-	id      uintptr        // ptrtoint of *funcValueWithSignature before lowering, opaque index (non-0) after lowering
-}
-
-// funcValueWithSignature is used before the func lowering pass.
-type funcValueWithSignature struct {
-	funcPtr   uintptr // ptrtoint of the actual function pointer
-	signature *uint8  // external *i8 with a name identifying the function signature
-}
-
-// getFuncPtr is a dummy function that may be used if the func lowering pass is
-// not used. It is generally too slow but may be a useful fallback to debug the
-// func lowering pass.
-func getFuncPtr(val funcValue, signature *uint8) uintptr {
-	return (*funcValueWithSignature)(unsafe.Pointer(val.id)).funcPtr
-}