Add test for undefined values equality checking

Author: AmirhosseinPoolad

vpr/test/test_undefined_value.cpp

@@ -0,0 +1,8 @@
+#include "vpr_types.h"
+#include "arch_types.h"
+#include "librrgraph_types.h"
+
+// Make sure the 'unknown value' constants in VPR, LibArchFPGA and LibRRGraph are all equal to the same value (-1)
+// Ideally these values should be independent of each other, but since they might be compared with each other in
+// the project we enforce that they all have the same value.
+static_assert(UNDEFINED == -1 && ARCH_FPGA_UNDEFINED_VAL == -1 && LIBRRGRAPH_UNDEFINED_VAL == -1, "The 'undefined value' constants in VPR, LibArchFPGA and LibRRGraph all must equal -1.");