RFR (S): Connection matrix should be char*, not bool*

[Aleksey Shipilev]

Hi,

C++ Standard guarantees sizeof(char) = 1. It does not guarantee the same for
sizeof(bool). Therefore, having char* matrix is safer. Here:
  http://cr.openjdk.java.net/~shade/shenandoah/matrix-byte/webrev.01/

Testing: hotspot_gc_shenandoah, jcstress -m quick with matrix verification

Thanks,
-Aleksey