runtime: remove thunk.s

Replace with uses of //go:linkname in Go files, direct use of name in .s files.
The only one that really truly needs a jump is reflect.call; the jump is now
next to the runtime.reflectcall assembly implementations.

Change-Id: Ie7ff3020a8f60a8e4c8645fe236e7883a3f23f46
Reviewed-on: https://go-review.googlesource.com/1962
Reviewed-by: Austin Clements <austin@google.com>
diff --git a/src/runtime/malloc.go b/src/runtime/malloc.go
index a056808..d7fca7f 100644
--- a/src/runtime/malloc.go
+++ b/src/runtime/malloc.go
@@ -387,6 +387,11 @@
 	return mallocgc(uintptr(typ.size), typ, flags)
 }
 
+//go:linkname reflect_unsafe_New reflect.unsafe_New
+func reflect_unsafe_New(typ *_type) unsafe.Pointer {
+	return newobject(typ)
+}
+
 // implementation of make builtin for slices
 func newarray(typ *_type, n uintptr) unsafe.Pointer {
 	flags := uint32(0)
@@ -399,6 +404,11 @@
 	return mallocgc(uintptr(typ.size)*n, typ, flags)
 }
 
+//go:linkname reflect_unsafe_NewArray reflect.unsafe_NewArray
+func reflect_unsafe_NewArray(typ *_type, n uintptr) unsafe.Pointer {
+	return newarray(typ, n)
+}
+
 // rawmem returns a chunk of pointerless memory.  It is
 // not zeroed.
 func rawmem(size uintptr) unsafe.Pointer {