test: add a test about .swiftsourceinfo file using Private directory

Author: nkcsgexi

test/Driver/sourceinfo_file.swift

@@ -0,0 +1,11 @@
+// RUN: %empty-directory(%t)
+// RUN: mkdir -p %t/build/Private
+// RUN: %swiftc_driver -driver-print-jobs -emit-module %s -emit-module-path %t/build/sourceinfo_file.swiftmodule -module-name sourceinfo_file | %FileCheck %s -check-prefix CHECK-PRIVATE
+
+// CHECK-PRIVATE: Private/sourceinfo_file.swiftsourceinfo
+
+// RUN: %empty-directory(%t/build)
+// RUN: %swiftc_driver -driver-print-jobs -emit-module %s -emit-module-path %t/build/sourceinfo_file.swiftmodule -module-name sourceinfo_file | %FileCheck %s -check-prefix CHECK-NOPRIVATE
+
+// CHECK-NOPRIVATE-NOT: Private/sourceinfo_file.swiftsourceinfo
+// CHECK-NOPRIVATE: sourceinfo_file.swiftsourceinfo