OWNERS: restrict fuzzer owners rule to files only (exclude dirs).

Bug: 1002923, 539572
Change-Id: Iecd42a6ac0748041a07acbb79d49a52611608fb4
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1816639
Auto-Submit: Max Moroz <mmoroz@chromium.org>
Reviewed-by: Dirk Pranke <dpranke@chromium.org>
Reviewed-by: John Abd-El-Malek <jam@chromium.org>
Commit-Queue: Max Moroz <mmoroz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#698642}

OWNERS

@@ -25,4 +25,4 @@ per-file PRESUBMIT*.py=dpranke@chromium.org
 per-file PRESUBMIT*.py=jochen@chromium.org
 per-file README.md=*
 per-file WATCHLISTS=*
-per-file *fuzz*=file://testing/libfuzzer/OWNERS
+per-file *fuzzer.*=file://testing/libfuzzer/OWNERS