crash_reporter: Mark the euid parameter as __unused.

This fixes an unused parameter warning.

Bug: 27378717
Change-Id: Ieb50dfd60a565e0cd77e8179c21cbe8e65ebdd9d

crash_collector.cc

diff --git a/crash_collector.cc b/crash_collector.cc
index 31d9f0f..d993576 100644
--- a/crash_collector.cc
+++ b/crash_collector.cc
@@ -189,7 +189,7 @@
   return true;
 }
 
-bool CrashCollector::GetCreatedCrashDirectoryByEuid(uid_t euid,
+bool CrashCollector::GetCreatedCrashDirectoryByEuid(uid_t euid __unused,
                                                     FilePath *crash_directory,
                                                     bool *out_of_capacity) {
   if (out_of_capacity) *out_of_capacity = false;