Fix XMM register count in CONTEXT_SetThreadContextOnPort in PAL

Author: John Chen (CLR)

src/pal/src/thread/context.cpp

@@ -1258,7 +1258,7 @@ CONTEXT_SetThreadContextOnPort(
             for (int i = 0; i < 8; i++)
                 memcpy((&State.__fpu_stmm0)[i].__mmst_reg, &lpContext->FltSave.FloatRegisters[i], 10);
 
-            memcpy(&State.__fpu_xmm0, &lpContext->Xmm0, 8 * 16);
+            memcpy(&State.__fpu_xmm0, &lpContext->Xmm0, 16 * 16);
 #else
 #error Unexpected architecture.
 #endif