Revert r209578:

Use C99 initializers for the struct sysent generated by MAKE_SYSENT().
C++ does not have designator-initializer facility of C99, not using this
in the header makes us friendly to C++ kernel modules, whoever wants
such schism.

Requested by:	mdf
MFC after:	6 days (not really)

sys/sys/sysent.h

@@ -151,10 +151,10 @@ struct syscall_module_data {
 
 #define	MAKE_SYSENT(syscallname)				\
 static struct sysent syscallname##_sysent = {			\
-	.sy_narg = (sizeof(struct syscallname ## _args )	\
+	(sizeof(struct syscallname ## _args )			\
 	    / sizeof(register_t)),				\
-	.sy_call = (sy_call_t *)& syscallname,			\
-	.sy_auevent = SYS_AUE_##syscallname,			\
+	(sy_call_t *)& syscallname,				\
+	SYS_AUE_##syscallname					\
 }
 
 #define SYSCALL_MODULE(name, offset, new_sysent, evh, arg)	\