Sema: validate deref operator type and value

test/cases/compile_errors/dereference_an_array.zig

@@ -0,0 +1,14 @@
+var s_buffer: [10]u8 = undefined;
+pub fn pass(in: []u8) []u8 {
+    var out = &s_buffer;
+    out.*.* = in[0];
+    return out.*[0..1];
+}
+
+export fn entry() usize { return @sizeOf(@TypeOf(&pass)); }
+
+// error
+// backend=stage2
+// target=native
+//
+// :4:10: error: cannot dereference non-pointer type '[10]u8'