Try to fix some analysis failures

Summary: Pull Request resolved: https://github.com/facebook/rocksdb/pull/6384

Test Plan: Wait and see the analysis result.

Differential Revision: D19781072

fbshipit-source-id: 75e7cb6ee619ebd289841eaabea03dd075c09d3b

options/options_parser.cc

@@ -331,7 +331,7 @@ Status RocksDBOptionsParser::ParseVersionNumber(const std::string& ver_name,
   for (int i = 0; i < max_count; ++i) {
     version[i] = 0;
   }
-  const int kBufferSize = 200;
+  constexpr int kBufferSize = 200;
   char buffer[kBufferSize];
   for (size_t i = 0; i < ver_string.size(); ++i) {
     if (ver_string[i] == '.') {
@@ -749,7 +749,7 @@ Status RocksDBOptionsParser::VerifyDBOptions(
       if (!AreEqualOptions(reinterpret_cast<const char*>(&base_opt),
                            reinterpret_cast<const char*>(&persisted_opt),
                            pair.second, pair.first, nullptr)) {
-        const size_t kBufferSize = 2048;
+        constexpr size_t kBufferSize = 2048;
         char buffer[kBufferSize];
         std::string base_value;
         std::string persisted_value;
@@ -787,7 +787,7 @@ Status RocksDBOptionsParser::VerifyCFOptions(
       if (!AreEqualOptions(reinterpret_cast<const char*>(&base_opt),
                            reinterpret_cast<const char*>(&persisted_opt),
                            pair.second, pair.first, persisted_opt_map)) {
-        const size_t kBufferSize = 2048;
+        constexpr size_t kBufferSize = 2048;
         char buffer[kBufferSize];
         std::string base_value;
         std::string persisted_value;