When terminating unix processes I forgot to check for negative

time differences.  This patch only sets the select timeout if
the difference between the requested and consumed time is 
positive.



[SVN r39612]

tools/build

@@ -1 +1 @@
-Subproject commit e468f99dbe8c297ce4513a6b5da8320ef2c75d2f
+Subproject commit b9c16aaaaa62cb54363b607022aae172169634ab