Add cLockAllowLeak attribute to RSLock and use it on DbgTransportTarget lock

The static g_DbgTransportTarget instance is destroyed after the host process's
main() returns. On Unix the dynamic loader does not invoke DbgDllMain
DLL_PROCESS_DETACH for mscordbi, so DbgTransportTarget::Shutdown() may never run
and the embedded RSLock m_sLock is left initialized at static destruction. The
RSLock destructor then asserts on the leak in checked builds and the host
aborts with exit 134, marking otherwise successful debugger tests as failures.

Add a new cLockAllowLeak bit to RSLock::ELockAttr. The destructor honors it by
suppressing the leak assert. Init the DbgTransportTarget lock with this bit set
to opt out of the assert, with a comment that the missing Shutdown call on Linux
is technically a bug tracked separately as low priority.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: kotlarmilos

src/coreclr/debug/di/dbgtransportmanager.cpp

@@ -74,7 +74,9 @@ DbgTransportTarget::DbgTransportTarget()
 // Initialization routine called only by the DbgTransportManager.
 HRESULT DbgTransportTarget::Init()
 {
-    m_sLock.Init("DbgTransportTarget Lock", RSLock::cLockFlat, RSLock::LL_DBG_TRANSPORT_TARGET_LOCK);
+    // The Unix loader does not invoke DbgDllMain DLL_PROCESS_DETACH for mscordbi at process exit,
+    // so Shutdown() may never run. Mark the lock as allowing leak to skip the destructor assert.
+    m_sLock.Init("DbgTransportTarget Lock", RSLock::cLockFlat | RSLock::cLockAllowLeak, RSLock::LL_DBG_TRANSPORT_TARGET_LOCK);
 
     return S_OK;
 }

src/coreclr/debug/di/rspriv.h

@@ -716,6 +716,10 @@ class RSLock
         // to count this lock in m_cTotalDbgApiLocks, which is asserted to be 0 on entry
         // to public APIs.  Example of such a lock: LL_SHIM_PROCESS_DISPOSE_LOCK
         cLockNonDbgApi  = 0x00000004,
+
+        // Skip the leak assert in the destructor. Use for static-lifetime locks
+        // whose owning shutdown path is not guaranteed to run.
+        cLockAllowLeak  = 0x00000008,
     };
 
     // To prevent deadlocks, we order all locks.

src/coreclr/debug/di/rspriv.inl

@@ -504,9 +504,9 @@ inline RSLock::RSLock()
 
 inline RSLock::~RSLock()
 {
-    // If this lock is still ininitialized, then no body ever deleted the critical section
-    // for it and we're leaking.
-    CONSISTENCY_CHECK_MSGF(!IsInit(), ("Leaking Critical section for RS Lock '%s'", m_szTag));
+    // If this lock is still initialized, then nobody ever deleted the critical section
+    // for it and we're leaking. cLockAllowLeak opts out of this assert.
+    CONSISTENCY_CHECK_MSGF(!IsInit() || (m_eAttr & cLockAllowLeak), ("Leaking Critical section for RS Lock '%s'", m_szTag));
 }
 #endif