Invalid assembly when several globals have the same name

[vbgl]

The compiler produces invalid assembly when compiling the following program:

inline fn get(inline u32 i) -> reg u32 {
  reg u32 r;
  global u32 g;
  g = i;
  r = g;
  return r;
}

export
fn main() -> reg u32 {
  reg u32 a b;
  a = get(0xa);
  b = get(0xb);
  b += a;
  return b;
}

Processing the generated assembly yields:

bug_871.s: Assembler messages:
bug_871.s:21: Error: symbol `G$g' is already defined

[vbgl]

Fixed by #907.