Suggest only active owners as code reviewers

Multiple people with code ownership privileges are no longer active
developers on the project. We should avoid bugging them to do code
reviews. Specifically, https://autoroll.skia.org/r/swiftshader-android
appears to randomly select someone from the OWNERS file to approve
merging SwiftShader updates into AOSP.

The annotation syntax is documented at:
https://android-review.googlesource.com/plugins/code-owners/Documentation/backend-find-owners.html#annotations

Bug: b/216637511
Change-Id: Ic400cf777481eed39be27377f78255b4dd440056
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/62008
Tested-by: Nicolas Capens <nicolascapens@google.com>
Reviewed-by: Alexis Hétu <sugoi@google.com>
diff --git a/OWNERS b/OWNERS
index 56d01f5..7415fb8 100644
--- a/OWNERS
+++ b/OWNERS
@@ -9,10 +9,11 @@
 
 nicolascapens@google.com
 sugoi@google.com
-shannonwoods@google.com
-chrisforbes@google.com
-cwallez@google.com
-amaiorano@google.com
-natsu@google.com
-schuffelen@google.com
-bclayton@google.com
\ No newline at end of file
+
+shannonwoods@google.com  #{LAST_RESORT_SUGGESTION}
+chrisforbes@google.com   #{LAST_RESORT_SUGGESTION}
+cwallez@google.com       #{LAST_RESORT_SUGGESTION}
+amaiorano@google.com     #{LAST_RESORT_SUGGESTION}
+natsu@google.com         #{LAST_RESORT_SUGGESTION}
+schuffelen@google.com    #{LAST_RESORT_SUGGESTION}
+bclayton@google.com      #{LAST_RESORT_SUGGESTION}
\ No newline at end of file