Fix ISOSDACInterface::GetThreadData reading the GC alloc context. (#1…

…04762)

* Fix ISOSDACInterface::GetThreadData reading the GC alloc context.

The RuntimeThreadLocals struct that the gc_alloc_context is in wasn't being added
to dump in Thread::EnumMemoryRegions.

src/coreclr/vm/threads.cpp

@@ -8067,6 +8067,15 @@ Thread::EnumMemoryRegions(CLRDataEnumMemoryFlags flags)
         }
     }
 
+    //
+    // Add the thread local variables like alloc_context, etc.
+    //
+
+    if (m_pRuntimeThreadLocals.IsValid())
+    {
+        m_pRuntimeThreadLocals.EnumMem();
+    }
+
     //
     // Try and do a stack trace and save information
     // for each part of the stack.  This is very vulnerable