PR go/83787
    compiler: pass int to makechan, call makechan64 when appropriate
    
    The update to 1.10beta1 changed makechan to take int instead of int64,
    and added a makechan64 call for large values.  Since the size is the
    last argument to makechan, the old compiler which always passed a
    64-bit int worked fine on 64-bit systems and little-endian 32-bit
    systems, but broke on big-endian 32-bit systems.  This CL fixes the
    compiler to use the appropriate types.
    
    This fixes GCC PR 83787.
    
    Reviewed-on: https://go-review.googlesource.com/88077

From-SVN: r256835