Remove unused exception parameters from a few files

Summary:
`-Wunused-exception-parameter` has identified an unused exception parameter. This diff removes it.

This:
```
try {
    ...
} catch (exception& e) {
    // no use of e
}
```
should instead be written as
```
} catch (exception&) {
```

If the code compiles, this is safe to land.

Reviewed By: dtolnay

Differential Revision: D89501752

fbshipit-source-id: 4c3ba0151af3f44d0f2fc23f12e3a808a9e1d86c

Author: r-barnes

folly/fibers/AtomicBatchDispatcher-inl.h

@@ -31,7 +31,7 @@ struct AtomicBatchDispatcher<InputT, ResultT>::DispatchBaton {
   }
 
   void setExpectedCount(size_t expectedCount) {
-    assert(expectedCount_ == 0 || !"expectedCount_ being set more than once");
+    assert(expectedCount_ == 0 && "expectedCount_ being set more than once");
     expectedCount_ = expectedCount;
     optEntries_.resize(expectedCount_);
   }
@@ -41,7 +41,7 @@ struct AtomicBatchDispatcher<InputT, ResultT>::DispatchBaton {
       optEntries_.resize(sequenceNumber + 1);
     }
     folly::Optional<Entry>& optEntry = optEntries_[sequenceNumber];
-    assert(!optEntry || !"Multiple inputs have the same token sequence number");
+    assert(!optEntry && "Multiple inputs have the same token sequence number");
     optEntry = Entry(std::move(input));
     return optEntry->promise.getFuture();
   }
@@ -65,8 +65,8 @@ struct AtomicBatchDispatcher<InputT, ResultT>::DispatchBaton {
 
       // Validate entries count same as expectedCount_
       assert(
-          optEntries_.size() == expectedCount_ ||
-          !"Entries vector did not have expected size");
+          optEntries_.size() == expectedCount_ &&
+          "Entries vector did not have expected size");
       std::vector<size_t> vecTokensNotDispatched;
       for (size_t i = 0; i < expectedCount_; ++i) {
         if (!optEntries_[i]) {