Debug info: Actually encode the Swift version number instead of constant 1.

<rdar://problem/18729762> CU's RuntimeVersion field should have the Swift runtime version number

Swift SVN r23087

lib/Basic/Version.cpp

@@ -42,6 +42,9 @@ SWIFT_MAKE_VERSION_STRING(SWIFT_VERSION_MAJOR,SWIFT_VERSION_MINOR)
 namespace swift {
 namespace version {
 
+std::pair<unsigned, unsigned> getSwiftNumericVersion() {
+  return { SWIFT_VERSION_MAJOR, SWIFT_VERSION_MINOR };
+}
 
 std::string getSwiftFullVersion() {
   std::string buf;