Resubmit "Refactor debuginfo-tests" again.

This was reverted due to the tests being run twice on some
build bots.  Each run had a slightly different configuration
due to the way in which it was being invoked.  This fixes
the problem (albeit in a somewhat hacky way).  Hopefully in
the future we can get rid of the workflow of running
debuginfo-tests as part of clang, and then this hack can
go away.

llvm-svn: 318697

debuginfo-tests/nested-struct.cpp

@@ -1,21 +0,0 @@
-// RUN: %clangxx %target_itanium_abi_host_triple -O0 -g %s -c -o %t.o
-// RUN: %test_debuginfo %s %t.o
-// Radar 9440721
-// If debug info for my_number() is emitted outside function foo's scope
-// then a debugger may not be able to handle it. At least one version of
-// gdb crashes in such cases.
-
-// DEBUGGER: ptype foo
-// CHECK: int (void)
-
-int foo() {
-  struct Local {
-    static int my_number() {
-      return 42;
-    }
-  };
-
-  int i = 0;
-  i = Local::my_number();
-  return i + 1;
-}