public enums + more public structs (libs/examples/tests)

vlib/sync/sync_nix.v

@@ -5,7 +5,7 @@
 module sync
 
 #include <pthread.h>
-struct Mutex {
+pub struct Mutex {
 	mutex C.pthread_mutex_t
 }
 

vlib/sync/sync_win.v

@@ -7,7 +7,7 @@ module sync
 // Mutex HANDLE
 type MHANDLE voidptr
 
-struct Mutex {
+pub struct Mutex {
 mut:
 	mx           MHANDLE    // mutex handle
 	state        MutexState // mutex state

vlib/sync/waitgroup.v

@@ -4,7 +4,7 @@
 
 module sync
 
-struct WaitGroup {
+pub struct WaitGroup {
 mut:
 	mu Mutex
 	active int