Add regression test for real array index error

Check that using a real valued expression as an array index is rejected
during elaboration.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>

ivtest/ivltests/array_index_real_fail.v

@@ -0,0 +1,12 @@
+// Check that real expressions can not be used as array indices.
+
+module test;
+
+  reg [1:0] a[1:0];
+  real r;
+
+  initial begin
+    a[r] = 2'b10;
+  end
+
+endmodule

ivtest/regress-vvp.list

@@ -6,6 +6,7 @@ always4A			vvp_tests/always4A.json
 always4B			vvp_tests/always4B.json
 analog1				vvp_tests/analog1.json
 analog2				vvp_tests/analog2.json
+array_index_real_fail		vvp_tests/array_index_real_fail.json
 array_packed_sysfunct		vvp_tests/array_packed_sysfunct.json
 array_packed_value_list		vvp_tests/array_packed_value_list.json
 array_packed_write_read		vvp_tests/array_packed_write_read.json

ivtest/vvp_tests/array_index_real_fail.json

@@ -0,0 +1,4 @@
+{
+    "type"   : "CE",
+    "source" : "array_index_real_fail.v"
+}