fix package resolution of nested typedefs (resolves #11)

test/basic/package_typedef_nested.sv

@@ -0,0 +1,24 @@
+package foo_pkg;
+
+    typedef struct packed {
+        logic [7:0] rsvd;
+        logic [7:0] parity;
+    } user_t;
+
+    typedef struct packed {
+        logic  valid;
+        user_t user;
+    } inp_t;
+
+    typedef struct packed {
+        logic valid;
+        logic opcode;
+    } out_t;
+
+endpackage
+
+module top (
+    input  foo_pkg::inp_t dat_i,
+    output foo_pkg::out_t dat_o
+);
+endmodule

test/basic/package_typedef_nested.v

@@ -0,0 +1,4 @@
+module top (dat_i, dat_o);
+    input wire [16:0] dat_i;
+    output wire [1:0] dat_o;
+endmodule