Event blocks just block all events

In a galaxy far, far away, event_blockage_t was intended to block only cetain
events. But it always just blocked everything. Eliminate the event block
mask.

tests/signal.in

@@ -2,7 +2,6 @@ function alarm --on-signal ALRM
   echo ALRM received
 end
 
-
 kill -s ALRM $fish_pid
 
 function anychild --on-process-exit 0
@@ -10,6 +9,17 @@ function anychild --on-process-exit 0
   echo $argv[1] $argv[3]
 end
 
+echo "command false:"
 command false
+echo "command true:"
 command true
+echo "command false | true:"
 command false | command true
+
+function test_blocks
+  block -l
+  command echo "This is the process whose exit event shuld be blocked"
+  echo "This should come before the event handler"
+end
+test_blocks
+echo "Now event handler should have run"

tests/signal.out

@@ -1,9 +1,17 @@
 ALRM received
+command false:
 PROCESS_EXIT 1
 JOB_EXIT 0
+command true:
 PROCESS_EXIT 0
 JOB_EXIT 0
+command false | true:
 PROCESS_EXIT 1
 PROCESS_EXIT 0
 JOB_EXIT 0
+This is the process whose exit event shuld be blocked
+This should come before the event handler
+PROCESS_EXIT 0
+JOB_EXIT 0
+Now event handler should have run
 PROCESS_EXIT 0