Enable bugprone-too-small-loop-variable clang-tidy check

Signed-off-by: Kevin Ottens <kevin.ottens@nextcloud.com>

.clang-tidy

@@ -4,6 +4,7 @@ Checks: '-*,
     bugprone-forward-declaration-namespace,
     bugprone-macro-parentheses,
     bugprone-narrowing-conversions,
+    bugprone-too-small-loop-variable,
     cppcoreguidelines-init-variables,
     misc-*,
     -misc-non-private-member-variables-in-classes,

test/benchmarks/benchlargesync.cpp

@@ -22,7 +22,7 @@ void addBunchOfFiles(int depth, const QString &path, FileModifier &fi) {
     }
     if (depth >= maxDepth)
         return;
-    for (char dirNum = 1; dirNum <= dirPerDir; ++dirNum) {
+    for (int dirNum = 1; dirNum <= dirPerDir; ++dirNum) {
         QString name = QStringLiteral("dir") + QString::number(dirNum);
         QString subPath = path.isEmpty() ? name : path + "/" + name;
         fi.mkdir(subPath);