cmd/gc: simplify code for c2go (more)

cmd/gc: simplify code for c2go (more)

- Remove more ? : expressions.
- Use uint32 **hash instead of uint32 *hash[] in function argument.
- Change array.c API to use int, not int32, to match Go's slices.
- Rename strlit to newstrlit, to avoid case-insensitive collision with Strlit.
- Fix a few incorrect printf formats.
- Rename a few variables from 'len' to n or length.
- Eliminate direct string editing building up names like convI2T.

Change-Id: I754cf553402ccdd4963e51b7039f589286219c29
Reviewed-on: https://go-review.googlesource.com/3278
Reviewed-by: Rob Pike <r@golang.org>