[x86/Linux] Mark several Windows-specific functions in excepx86.cpp a…

…s NYI (#8424)

* Mark several Windows-specific functions as NYI

* Use FEATURE_PAL instead of PLATFORM_UNIX

* Revert the change in threads.h

src/vm/i386/excepx86.cpp

@@ -373,6 +373,7 @@ CPFH_AdjustContextForThreadSuspensionRace(CONTEXT *pContext, Thread *pThread)
 {
  WRAPPER_NO_CONTRACT;
 
+#ifndef FEATURE_PAL
  PCODE f_IP = GetIP(pContext);
  if (Thread::IsAddrOfRedirectFunc((PVOID)f_IP)) {
 
@@ -429,6 +430,9 @@ CPFH_AdjustContextForThreadSuspensionRace(CONTEXT *pContext, Thread *pThread)
  SetIP(pContext, GetIP(pThread->m_OSContext) - 1);
  STRESS_LOG1(LF_EH, LL_INFO100, "CPFH_AdjustContextForThreadSuspensionRace: Case 4 setting IP = %x\n", pContext->Eip);
  }
+#else
+ PORTABILITY_ASSERT("CPFH_AdjustContextForThreadSuspensionRace");
+#endif
 }
 #endif // FEATURE_HIJACK
 
@@ -2009,12 +2013,17 @@ PEXCEPTION_REGISTRATION_RECORD GetCurrentSEHRecord()
 
 PEXCEPTION_REGISTRATION_RECORD GetFirstCOMPlusSEHRecord(Thread *pThread) {
  WRAPPER_NO_CONTRACT;
+#ifndef FEATURE_PAL
  EXCEPTION_REGISTRATION_RECORD *pEHR = *(pThread->GetExceptionListPtr());
  if (pEHR == EXCEPTION_CHAIN_END || IsUnmanagedToManagedSEHHandler(pEHR)) {
  return pEHR;
  } else {
  return GetNextCOMPlusSEHRecord(pEHR);
  }
+#else // FEATURE_PAL
+ PORTABILITY_ASSERT("GetFirstCOMPlusSEHRecord");
+ return NULL;
+#endif // FEATURE_PAL
 }
 
 
@@ -2040,7 +2049,11 @@ PEXCEPTION_REGISTRATION_RECORD GetPrevSEHRecord(EXCEPTION_REGISTRATION_RECORD *n
 VOID SetCurrentSEHRecord(EXCEPTION_REGISTRATION_RECORD *pSEH)
 {
  WRAPPER_NO_CONTRACT;
+#ifndef FEATURE_PAL
  *GetThread()->GetExceptionListPtr() = pSEH;
+#else // FEATURE_PAL
+ _ASSERTE("NYI");
+#endif // FEATURE_PAL
 }
 
 
@@ -2077,6 +2090,7 @@ BOOL PopNestedExceptionRecords(LPVOID pTargetSP, BOOL bCheckForUnknownHandlers)
  STATIC_CONTRACT_GC_NOTRIGGER;
  STATIC_CONTRACT_SO_TOLERANT;
 
+#ifndef FEATURE_PAL
  PEXCEPTION_REGISTRATION_RECORD pEHR = GetCurrentSEHRecord();
 
  while ((LPVOID)pEHR < pTargetSP)
@@ -2132,6 +2146,10 @@ BOOL PopNestedExceptionRecords(LPVOID pTargetSP, BOOL bCheckForUnknownHandlers)
  SetCurrentSEHRecord(pEHR);
  }
  return FALSE;
+#else // FEATURE_PAL
+ PORTABILITY_ASSERT("PopNestedExceptionRecords");
+ return FALSE;
+#endif // FEATURE_PAL
 }
 
 //