Generate substantially better code when there are a limited number of exits from the extracted region.  If the return has 0 or 1 exit blocks, the new function returns void.  If it has 2 exits, it returns bool, otherwise it returns a ushort as before.
Generate substantially better code when there are a limited number of exits
from the extracted region.  If the return has 0 or 1 exit blocks, the new
function returns void.  If it has 2 exits, it returns bool, otherwise it
returns a ushort as before.

This allows us to use a conditional branch instruction when there are two
exit blocks, as often happens during block extraction.


git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@13481 91177308-0d34-0410-b5e6-96231b3b80d8

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