<rdar://problem/15296388>

Fix a crasher that would occur if one tried to read memory as characters of some size != 1, e.g.
x -f c -s 10  buffer

This commit tries to do the right thing and uses the byte-size as the number of elements, unless both are specified and the number of elements is != 1
In this latter case (e.g. x -f c -s 10 -c 3  buffer) one could multiply the two and read 30 characters, but it seems a stretch in mind reading.

llvm-svn: 193659