Change order of evaluation for certain indexing operations.

'.foo[.bar]' used to parse like '.foo | .bar as $b | .[$b]',
now it parses like '.bar as $b | .foo | .[$b]'.

parser.y

@@ -133,7 +133,7 @@ static block gen_dictpair(block k, block v) {
 }
 
 static block gen_index(block obj, block key) {
-  return BLOCK(obj, gen_subexp(key), gen_op_simple(INDEX));
+  return BLOCK(gen_subexp(key), obj, gen_op_simple(INDEX));
 }
 
 static block gen_binop(block a, block b, int op) {

testdata

@@ -464,3 +464,7 @@ unique
 [min,max,min_by(.),max_by(.)]
 []
 [null,null,null,null]
+
+.foo[.baz]
+{"foo":{"bar":4},"baz":"bar"}
+4