emoji: repair one-shot candidate selection

ipc.h

@@ -7,6 +7,7 @@
 
 /*
  * Request: [want-preedit, modifiers, key byte 0, ..., key byte 3].
+ * Only Mmask modifier bits are retained.
  * Response: [eaten, commit-length-low, commit-length-high, commit...],
  * followed, when requested, by
  * [preedit-length-low, preedit-length-high, preedit...].
@@ -22,13 +23,14 @@ enum
 	Kesc = Kspec|0x1b,
 	Kup = Kspec|0x52,
 	Kdown = Kspec|0x54,
-	Kshift = Kspec|0xe1,
-	Ksuper = Kspec|0xeb,
+	Kmodfirst = Kspec|0xe1,
+	Kmodlast = Kspec|0xee,
 
 	Mshift = 1<<0,
 	Mctrl = 1<<2,
 	Malt = 1<<3,
 	Msuper = 1<<6,
+	Mmask = Mshift|Mctrl|Malt|Msuper,
 
 	Ipcreqsz = 6,
 	Ipclensz = 2,