[clang-format] Hoist vector allocation out of loop. NFC.

llvm-svn: 239604
diff --git a/clang/lib/Format/FormatToken.cpp b/clang/lib/Format/FormatToken.cpp
index 88678ca..316171d 100644
--- a/clang/lib/Format/FormatToken.cpp
+++ b/clang/lib/Format/FormatToken.cpp
@@ -203,11 +203,14 @@
 
   // We can never place more than ColumnLimit / 3 items in a row (because of the
   // spaces and the comma).
-  for (unsigned Columns = 1; Columns <= Style.ColumnLimit / 3; ++Columns) {
+  unsigned MaxItems = Style.ColumnLimit / 3;
+  std::vector<unsigned> MinSizeInColumn;
+  MinSizeInColumn.reserve(MaxItems);
+  for (unsigned Columns = 1; Columns <= MaxItems; ++Columns) {
     ColumnFormat Format;
     Format.Columns = Columns;
     Format.ColumnSizes.resize(Columns);
-    std::vector<unsigned> MinSizeInColumn(Columns, UINT_MAX);
+    MinSizeInColumn.assign(Columns, UINT_MAX);
     Format.LineCount = 1;
     bool HasRowWithSufficientColumns = false;
     unsigned Column = 0;