Merge #12881: Minor optimizations to bech32::Decode(); add tests.

60f61f9 Tighten up bech32::Decode(); add tests. (murrayn)

Pull request description:

  Just a few minor optimizations to bech32::Decode():

  1) optimize the order and logic of the conditionals
  2) get rid of subsequent '(c < 33 || c > 126)' check which is redundant (already performed above)
  3) add a couple more bech32 tests (mixed-case)

Tree-SHA512: e41af834c8f6b7d34c22c28b724df42c60f72e00df616e70a12efbc4271d15d80627fe1bc36845caf29f615c238499a566298a863cbe119fef457287231053c8

src/test/bech32_tests.cpp

@@ -57,6 +57,8 @@ BOOST_AUTO_TEST_CASE(bip173_testvectors_invalid)
         "A1G7SGD8",
         "10a06t8",
         "1qzzfhee",
+        "a12UEL5L",
+        "A12uEL5L",
     };
     for (const std::string& str : CASES) {
         auto ret = bech32::Decode(str);