Convert Block::event_blocks to a bool

We only increment it and check if it's non-zero, we never decrement or check the
actual count. As such, change it to a bool and bring the size of `Block` down
from 32 to 24 bytes.

src/builtins/block.rs

@@ -139,7 +139,7 @@ pub fn block(parser: &Parser, streams: &mut IoStreams, args: &mut [&wstr]) -> Op
     };
 
     if have_block {
-        parser.block_at_index_mut(block_idx).unwrap().event_blocks += 1;
+        parser.block_at_index_mut(block_idx).unwrap().event_blocks |= true;
     } else {
         parser.global_event_blocks.fetch_add(1, Ordering::Relaxed);
     }

src/event.rs

@@ -267,7 +267,7 @@ impl Event {
     /// Test if specified event is blocked.
     fn is_blocked(&self, parser: &Parser) -> bool {
         for block in parser.blocks().iter().rev() {
-            if block.event_blocks != 0 {
+            if block.event_blocks {
                 return true;
             }
         }

src/parser.rs

@@ -61,6 +61,9 @@ pub enum BlockData {
 /// block_t represents a block of commands.
 #[derive(Default)]
 pub struct Block {
+    /// Type of block.
+    block_type: BlockType,
+
     /// [`BlockType`]-specific data.
     ///
     /// Ideally this would be coalesced into `BlockType` but we currently require that to implement
@@ -70,8 +73,8 @@ pub struct Block {
     /// we store them in a `Box` to reduce the size of the `Block` itself.
     pub data: Option<Box<BlockData>>,
 
-    /// List of event blocks.
+    /// Pseudo-counter of event blocks
-    pub event_blocks: u64,
+    pub event_blocks: bool,
 
     /// Name of the file that created this block
     pub src_filename: Option<Arc<WString>>,
@@ -84,9 +87,6 @@ pub struct Block {
     /// This will saturate at the 65,535th line of a single fish script. I think that's ok!
     pub src_lineno: Option<NonZeroU16>,
 
-    /// Type of block.
-    block_type: BlockType,
-
     /// Whether we should pop the environment variable stack when we're popped off of the block
     /// stack.
     pub wants_pop_env: bool,