scripted-diff: Use inline constexpr over (static) const

Both are fine and this refactor shouldn't change any behavior.

However, inline constexpr will ensure each symbol has a single address
across all TU, making the release binary smaller.

Note, a follow-up commit will deal with string literals (const char*)
and other static const, which can not be constexpr (e.g. std::vector).

-BEGIN VERIFY SCRIPT-
 # Limit to types that can be constexpr
 type='bool|CAmount|size_t|((signed|unsigned) )?int|u?int[0-9]+_t|std::array|DatabaseFormat|CFeeRate|std::streamsize'
 sed -i --regexp-extended "s/^(static )?const (${type})\>/inline constexpr \2/" $( \
   git grep -l --extended-regexp "^(static )?const " -- \
     '*.h' \
     ':(exclude)src/leveldb' \
     ':(exclude)src/secp256k1' \
 )
-END VERIFY SCRIPT-

src/httpserver.h

@@ -32,15 +32,15 @@ class SignalInterrupt;
 /**
  * The default value for `-rpcthreads`. This number of threads will be created at startup.
  */
-static const int DEFAULT_HTTP_THREADS=16;
+inline constexpr int DEFAULT_HTTP_THREADS=16;
 
 /**
  * The default value for `-rpcworkqueue`. This is the maximum depth of the work queue,
  * we don't allocate this number of work queue items upfront.
  */
-static const int DEFAULT_HTTP_WORKQUEUE=64;
+inline constexpr int DEFAULT_HTTP_WORKQUEUE=64;
 
-static const int DEFAULT_HTTP_SERVER_TIMEOUT=30;
+inline constexpr int DEFAULT_HTTP_SERVER_TIMEOUT=30;
 
 enum class HTTPRequestMethod {
     UNKNOWN,