Merge #14495: build: Warn (don't fail!) on spelling errors

c32cf6a Add ignored word: mut (practicalswift)
4ae50da Revert "qa: Fix codespell error and have lint-spelling error instead of warn" (practicalswift)

Pull request description:

  Revert `codespell` policy change introduced in #14179.

  Context: bitcoin/bitcoin#13954 (comment)

Tree-SHA512: 4606b19bb32cdd661f90b3778759818d3493e5ed1a4a2f95982f07eeb6b9c889bc8d53cde31706e0a3b9524c3d3a7378f1b769a60baeb0d00da4c68fd3068114

Author: sipa

test/lint/lint-spelling.ignore-words.txt

@@ -1,6 +1,7 @@
 cas
 hights
 mor
+mut
 objext
 unselect
 useable

test/lint/lint-spelling.sh

@@ -9,10 +9,7 @@
 
 export LC_ALL=C
 
-EXIT_CODE=0
 IGNORE_WORDS_FILE=test/lint/lint-spelling.ignore-words.txt
 if ! codespell --check-filenames --disable-colors --quiet-level=7 --ignore-words=${IGNORE_WORDS_FILE} $(git ls-files -- ":(exclude)build-aux/m4/" ":(exclude)contrib/seeds/*.txt" ":(exclude)depends/" ":(exclude)doc/release-notes/" ":(exclude)src/leveldb/" ":(exclude)src/qt/locale/" ":(exclude)src/secp256k1/" ":(exclude)src/univalue/"); then
     echo "^ Warning: codespell identified likely spelling errors. Any false positives? Add them to the list of ignored words in ${IGNORE_WORDS_FILE}"
-    EXIT_CODE=1
 fi
-exit ${EXIT_CODE}