fix(ipc): preserve legacy preedit and bound client waits

ipc.h

@@ -50,6 +50,7 @@ enum
 	Ipcresphdrsz = 1 + Ipclensz,
 	Ipcfieldmax = 256,
 	Ipcmaxresp = Ipcresphdrsz + Ipcfieldmax + Ipclensz + Ipcfieldmax,
+	Ipcwaitms = 250,
 };
 
 enum
@@ -64,8 +65,9 @@ typedef struct Ipcresp Ipcresp;
 struct Ipcresp
 {
 	int	eaten;
-	size_t	ncommit;
-	size_t	npreedit;
+	/* Bytes copied to each caller buffer, excluding its trailing NUL. */
+	size_t	commitlen;
+	size_t	preeditlen;
 };
 
 void	ipcpackreq(unsigned char[Ipcreqsz], int, uint32_t, uint32_t);