CachedAppOptimizer: fix fd leak.

errno isn't modified when a syscall returns successfully: this would
leak if errno was already non-zero before entering this function.

Bug: 172518739
Test: none
Change-Id: I38050863ceca226a9c2d143c85e0713c6a6fe511
Merged-In: I38050863ceca226a9c2d143c85e0713c6a6fe511
1 file changed