Remove unused variables in fbit/itstorage/data_crawler/thread/Threade…

…dCrawler.cpp (#538)

Summary:
X-link: facebookresearch/fbpcs#2397

Pull Request resolved: #538

LLVM-15 has a warning `-Wunused-but-set-variable` which we treat as an error because it's so often diagnostic of a code issue. Unused variables can compromise readability or, worse, performance.

This diff either (a) removes an unused variable and, possibly, it's associated code, or (b) qualifies the variable with `[[maybe_unused]]`, mostly in cases where the variable _is_ used, but, eg, in an `assert` statement that isn't present in production code.

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Reviewed By: palmje

Differential Revision: D56022415

fbshipit-source-id: 65aa2b310e39ff134bf6dd8a82e3a539c3033660

fbpcf/mpc_std_lib/unified_data_process/data_processor/DataProcessor_impl.h

@@ -23,7 +23,6 @@ typename IDataProcessor<schedulerId>::SecString
 DataProcessor<schedulerId>::processMyData(
     const std::vector<std::vector<unsigned char>>& plaintextData,
     size_t outputSize) {
-  size_t dataSize = plaintextData.size();
   size_t dataWidth = plaintextData.at(0).size();
   std::vector<uint64_t> indexes(plaintextData.size());
   // generate 0 to n-1 vector