cmd/compile: do not inline functions marked cgo_unsafe_args

Now the net tests pass with -gcflags '-l=4'.

Fixes #18125.

Change-Id: I4e3a46eb0cb3a93b203e74f5bc99c5822331f535
Reviewed-on: https://go-review.googlesource.com/33722Reviewed-by: Keith Randall <khr@golang.org>

src/cmd/compile/internal/gc/inl.go

@@ -107,6 +107,12 @@ func caninl(fn *Node) {
 		return
 	}
 
+	// If marked "go:cgo_unsafe_args", don't inline
+	if fn.Func.Pragma&CgoUnsafeArgs != 0 {
+		reason = "marked go:cgo_unsafe_args"
+		return
+	}
+
 	// If fn has no body (is defined outside of Go), cannot inline it.
 	if fn.Nbody.Len() == 0 {
 		reason = "no function body"