[Format] Use llvm::min_element (NFC) (#143725)

llvm::min_elements allows us to pass a range.

clang/lib/Format/MacroCallReconstructor.cpp

@@ -528,7 +528,7 @@ MacroCallReconstructor::createUnwrappedLine(const ReconstructedLine &Line,
       // 1. One level below the current line's level.
       // 2. At the correct level relative to each other.
       unsigned MinChildLevel =
-          std::min_element(N->Children.begin(), N->Children.end(),
+          llvm::min_element(N->Children,
                             [](const auto &E1, const auto &E2) {
                               return E1->Level < E2->Level;
                             })