fix sometimes call layoutsubviews in cycle

iOS/Pod/Classes/Shader/DoricLayouts.m

@@ -115,10 +115,12 @@ - (void)requestLayout {
         return;
     }
     self.waitingLayout = YES;
+    __weak typeof(self) _self = self;
     dispatch_async(dispatch_get_main_queue(), ^{
-        self.waitingLayout = NO;
+        __strong typeof(_self) self = _self;
         [self sizeToFit];
         [self layout];
+        self.waitingLayout = NO;
     });
 }
 
@@ -127,6 +129,13 @@ - (void)layoutSubviews {
     [self requestLayout];
 }
 
+- (void)setNeedsLayout {
+    if (self.waitingLayout) {
+        return;
+    }
+    [super setNeedsLayout];
+}
+
 - (void)layout {
     [self.subviews enumerateObjectsUsingBlock:^(__kindof UIView *child, NSUInteger idx, BOOL *stop) {
         if ([child isKindOfClass:[DoricLayoutContainer class]]) {