Fix thread hijack starvation issue

Author: filipnavara

src/coreclr/vm/threadsuspend.cpp

@@ -4783,7 +4783,16 @@ StackWalkAction SWCB_GetExecutionState(CrawlFrame *pCF, VOID *pData)
 #endif
                         }
 #elif defined(TARGET_X86)
-                        pES->m_ppvRetAddrPtr = (void **) pRDT->PCTAddr;
+                        if (pRDT->PCTAddr == 0)
+                        {
+                            // Initial context doesn't have PCTAddr so we have to compute it
+                            EECodeInfo codeInfo(pRDT->ControlPC);
+                            pES->m_ppvRetAddrPtr = (void **) (EECodeManager::GetCallerSp(pRDT) - codeInfo.GetCodeManager()->GetStackParameterSize(&codeInfo) - sizeof(void*));
+                        }
+                        else
+                        {
+                            pES->m_ppvRetAddrPtr = (void **) pRDT->PCTAddr;
+                        }
 #elif defined(TARGET_AMD64)
                         pES->m_ppvRetAddrPtr = (void **) (EECodeManager::GetCallerSp(pRDT) - sizeof(void*));
 #else // TARGET_X86 || TARGET_AMD64