cmd/compile: export the Func.Endlineno field

This CL exports the Func.Endlineno value for inlineable functions.
It is needed to grab the source code of an imported function
inlined into the function specified in $GOSSAFUNC.

See CL 126606 for details.

Updates #25904

Change-Id: I1e259e20445e4109b4621a95abb5bde1be457af1
Reviewed-on: https://go-review.googlesource.com/126605
Run-TryBot: Yury Smolsky <yury@smolsky.by>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>

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

@@ -952,6 +952,16 @@ func (w *exportWriter) funcExt(n *Node) {
 		if n.Func.ExportInline() {
 			w.p.doInline(n)
 		}
+
+		// Endlineno for inlined function.
+		if n.Name.Defn != nil {
+			w.pos(n.Name.Defn.Func.Endlineno)
+		} else {
+			// When the exported node was defined externally,
+			// e.g. io exports atomic.(*Value).Load or bytes exports errors.New.
+			// Keep it as we don't distinguish this case in iimport.go.
+			w.pos(n.Func.Endlineno)
+		}
 	} else {
 		w.uint64(0)
 	}

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

@@ -679,6 +679,7 @@ func (r *importReader) funcExt(n *Node) {
 		n.Func.Inl = &Inline{
 			Cost: int32(u - 1),
 		}
+		n.Func.Endlineno = r.pos()
 	}
 }