Use int[] rather than IntList for RawText hashes

Use int[] rather than IntList for RawText hashes

We know exactly how many lines we need by the time we compute our
per-line hashes, as we have already built the lines IntList to give
us the starting position of each line in the buffer.  Using that
we can properly size the array, and don't need the dynamic growing
feature of IntList.  So drop the indirection and just use a fixed
size array.

Change-Id: I5c8c592514692a8abff51e5928aedcf71e100365
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>