Bug 1602757: Add prealloc as a type for processes in about:support r=flod,fluent-reviewers

Differential Revision: https://phabricator.services.mozilla.com/D76189

toolkit/locales/en-US/toolkit/global/processTypes.ftl

@@ -31,3 +31,6 @@ process-type-gpu = GPU
 
 # process used to perform network operations
 process-type-socket = Socket
+
+# process preallocated; may change to other types
+process-type-prealloc = Preallocated