rlz: Silence spam from RecursiveCrossProcessLock

Change perror() to VPLOG() to avoid spamming the console with these
errors (they reliably occur on the login screen).

BUG=463306
TEST=build, boot, & login to pixel

Review URL: https://codereview.chromium.org/1096203003

Cr-Commit-Position: refs/heads/master@{#326621}

rlz/lib/recursive_cross_process_lock_posix.cc

@@ -43,7 +43,7 @@ bool RecursiveCrossProcessLock::TryGetCrossProcessLock(
     CHECK(file_lock_ == -1);
     file_lock_ = open(lock_filename.value().c_str(), O_RDWR | O_CREAT, 0666);
     if (file_lock_ == -1) {
-      perror("open");
+      VPLOG(1) << "Failed to open: " << lock_filename.value();
       return false;
     }
 
@@ -58,7 +58,7 @@ bool RecursiveCrossProcessLock::TryGetCrossProcessLock(
     }
 
     if (flock_result == -1) {
-      perror("flock");
+      VPLOG(1) << "Failed flock: " << lock_filename.value();
       close(file_lock_);
       file_lock_ = -1;
       return false;