[libc++] Fix style

Forgot to run `clang-format` before.

Author: tinnamchoi

libcxx/src/filesystem/path.cpp

@@ -292,7 +292,7 @@ path path::lexically_relative(const path& base) const {
   // return a path constructed with 'n' dot-dot elements, followed by the
   // elements of '*this' after the mismatch.
   path Result;
-  constexpr size_t ElemSize = 2; // ".."
+  constexpr size_t ElemSize      = 2; // ".."
   constexpr size_t SeparatorSize = 1; // separator is always a single char
   Result.__reserve(ElemCount * (ElemSize + SeparatorSize) + SeparatorSize + PP.Path.size());
   while (ElemCount--)