message_flags: Add missing set_global import.
message_flags: Add missing set_global import.

kou/zulip,kou/zulip,zulip/zulip,punchagan/zulip,kou/zulip,rht/zulip,eeshangarg/zulip,punchagan/zulip,andersk/zulip,andersk/zulip,rht/zulip,punchagan/zulip,punchagan/zulip,punchagan/zulip,andersk/zulip,andersk/zulip,andersk/zulip,hackerkid/zulip,hackerkid/zulip,punchagan/zulip,zulip/zulip,hackerkid/zulip,eeshangarg/zulip,punchagan/zulip,eeshangarg/zulip,eeshangarg/zulip,eeshangarg/zulip,zulip/zulip,rht/zulip,rht/zulip,kou/zulip,hackerkid/zulip,zulip/zulip,andersk/zulip,eeshangarg/zulip,andersk/zulip,zulip/zulip,zulip/zulip,rht/zulip,kou/zulip,rht/zulip,kou/zulip,eeshangarg/zulip,rht/zulip,hackerkid/zulip,hackerkid/zulip,hackerkid/zulip,kou/zulip,zulip/zulip