Use FindReportInEquivalenceClass to identify all the nodes used for the...

Use FindReportInEquivalenceClass to identify all the nodes used for the trimmed graph (in BugReporter).  This fixes a problem where a leak that happened to occur on both an exit() path and a non-exit() path was getting reported with the exit() path (which users don't care about).

This fixes:

<rdar://problem/8331641> leak reports should not show paths that end with exit() (but ones that don't end with exit())

llvm-svn: 113524