BUG: When byte order is not known at compile time make sure NeedSwap in cmELF is still initialized.

Source/cmELF.cxx

@@ -85,6 +85,8 @@ public:
     this->NeedSwap = (this->ByteOrder == ByteOrderMSB);
 #elif cmsys_CPU_ENDIAN_ID == cmsys_CPU_ENDIAN_ID_BIG
     this->NeedSwap = (this->ByteOrder == ByteOrderLSB);
+#else
+    this->NeedSwap = false; // Final decision is at runtime anyway.
 #endif
 
     // We have not yet loaded the section info.