cgen: optimize/generalize typ method

vlib/time/time.v

@@ -61,7 +61,8 @@ pub enum FormatDelimiter {
 	space
 }
 
-pub struct C.time_t {}
+// TODO: C.time_t. works in v2
+type time_t voidptr
 
 pub struct C.timeval {
 	tv_sec  u64
@@ -70,7 +71,7 @@ pub struct C.timeval {
 
 fn C.localtime(int) &C.tm
 
-fn C.time(int) C.time_t
+fn C.time(int) time_t
 
 // now returns current local time.
 pub fn now() Time {

vlib/v/gen/cgen.v

@@ -148,10 +148,9 @@ pub fn (g mut Gen) typ(t table.Type) string {
 	}
 	if styp.starts_with('C__') {
 		styp = styp[3..]
-	}
-	if styp in ['stat', 'dirent*', 'tm', 'tm*', 'winsize', 'sigaction', 'timeval'] {
-		// TODO perf and other C structs
-		styp = 'struct $styp'
+		if sym.kind == .struct_ {
+			styp = 'struct $styp'
+		}
 	}
 	if table.type_is_optional(t) {
 		styp = 'Option_' + styp