tilelink2: move general-purpose code out of tilelink2 package

src/main/scala/diplomacy/package.scala

@@ -0,0 +1,10 @@
+import Chisel._
+import chisel3.internal.sourceinfo.{SourceInfo, SourceLine, UnlocatableSourceInfo}
+
+package object diplomacy
+{
+  def sourceLine(sourceInfo: SourceInfo, prefix: String = " (", suffix: String = ")") = sourceInfo match {
+    case SourceLine(filename, line, col) => s"$prefix$filename:$line:$col$suffix"
+    case _ => ""
+  }
+}