[logging] add lint-logs.sh to check for newline termination.

Check that all calls to LogPrintf() are terminated by a newline,
except those that are explicitly marked as 'continued' logs.

contrib/devtools/lint-logs.sh

@@ -0,0 +1,25 @@
+#!/bin/bash
+#
+# Copyright (c) 2018 The Bitcoin Core developers
+# Distributed under the MIT software license, see the accompanying
+# file COPYING or http://www.opensource.org/licenses/mit-license.php.
+#
+# Check that all logs are terminated with '\n'
+#
+# Some logs are continued over multiple lines. They should be explicitly
+# commented with \* Continued *\
+#
+# There are some instances of LogPrintf() in comments. Those can be
+# ignored
+
+
+UNTERMINATED_LOGS=$(git grep "LogPrintf(" -- "*.cpp" | \
+    grep -v '\\n"' | \
+    grep -v "/\* Continued \*/" | \
+    grep -v "LogPrintf()")
+if [[ ${UNTERMINATED_LOGS} != "" ]]; then
+    echo "All calls to LogPrintf() should be terminated with \\n"
+    echo
+    echo "${UNTERMINATED_LOGS}"
+    exit 1
+fi