Statement expression as a sub-expression fails resolution

[Rob Schluntz]

  int main( int argc, char * argv[] ) {
    5+({
      int __result = 0;
      __result;
    });
  }

It seems the resolver has a hard time when a statement expression is a subexpression and contains variables.

[Rob Schluntz <rschlunt@…>]

In 5e2c348:

Assign a result type to StmtExpr after resolution [fixes #79]