Revert "Revert "Truncate vendor snapshot header glob list after filtering it""

This reverts commit 758140ceaea47c63fb4dfda99c3a352899e58973.

Reason for revert: modifying glob results no longer corrupts cache after aosp/1557261

Change-Id: Id94f1f5835a93e83dc9f465627913b91908d3560
diff --git a/cc/library.go b/cc/library.go
index 73ed969..29a3c69 100644
--- a/cc/library.go
+++ b/cc/library.go
@@ -481,6 +481,7 @@
 			}
 			j++
 		}
+		glob = glob[:j]
 	}
 
 	// Collect generated headers