Global const array initialization broke with references

[Rob Schluntz]

const int fred[1] = { -2 }; // fails for const and negative value

test.c:8 error: No reasonable alternatives for expression Cast of:
  Applying untyped: 
    Name: ?[?]
  ...to: 
    Variable Expression: fred: array of const signed int with dimension of Cast of:
          constant expression (1 1: one_t)
        to:
          long unsigned int
        with environment:
          Types:
          Non-types:


    Variable Expression: _index0: signed int


to:
  reference to signed int

error: No reasonable alternatives for expression Cast of:
  Applying untyped: 
    Name: ?[?]
  ...to: 
    Variable Expression: fred: array of const signed int with dimension of Cast of:
          constant expression (1 1: one_t)
        to:
          long unsigned int
        with environment:
          Types:
          Non-types:


    Variable Expression: _index0: signed int


to:
  reference to signed int

[Rob Schluntz <rschlunt@…>]

In 0c6596f:

Handle difference between reference casting and implicit conversion costs [fixes #39]