Split FreelistFind into FreelistFindFirst and FreelistFindLast so that the interface exactly matches the CBS interface.
Fix errors in freelist.c: missing computation of size in FreelistBlockSetLimit; update linked list correct in coalesceRight case in FreelistInsert.
Avoid compiler warnings in freelist.c.
In cbs.c: use $U for Booleans ($B is for bit tables).
Copied from Perforce
Change: 182397
ServerID: perforce.ravenbrook.com
No need for <string.h> in mpsi.c (this defines a function "index" on Linux).
Need more headers in range.c so that it will compile on its own.
Need UNUSED() declarations for some variables in cbstest.c.
Copied from Perforce
Change: 182113
ServerID: perforce.ravenbrook.com
