[libc++] Format the code base (#74334)

This patch runs clang-format on all of libcxx/include and libcxx/src, in
accordance with the RFC discussed at [1]. Follow-up patches will format
the benchmarks, the test suite and remaining parts of the code. I'm
splitting this one into its own patch so the diff is a bit easier to
review.

This patch was generated with:

   find libcxx/include libcxx/src -type f \
      | grep -v 'module.modulemap.in' \
      | grep -v 'CMakeLists.txt' \
      | grep -v 'README.txt' \
      | grep -v 'libcxx.imp' \
      | grep -v '__config_site.in' \
      | xargs clang-format -i

A Git merge driver is available in libcxx/utils/clang-format-merge-driver.sh
to help resolve merge and rebase issues across these formatting changes.

[1]: https://discourse.llvm.org/t/rfc-clang-formatting-all-of-libc-once-and-for-all
diff --git a/libcxx/src/valarray.cpp b/libcxx/src/valarray.cpp
index f377e0f..6ef1f1c 100644
--- a/libcxx/src/valarray.cpp
+++ b/libcxx/src/valarray.cpp
@@ -18,40 +18,32 @@
 
 template void valarray<size_t>::resize(size_t, size_t);
 
-void
-gslice::__init(size_t __start)
-{
-    valarray<size_t> __indices(__size_.size());
-    size_t __k = __size_.size() != 0;
-    for (size_t __i = 0; __i < __size_.size(); ++__i)
-        __k *= __size_[__i];
-    __1d_.resize(__k);
-    if (__1d_.size())
-    {
-        __k = 0;
-        __1d_[__k] = __start;
-        while (true)
-        {
-            size_t __i = __indices.size() - 1;
-            while (true)
-            {
-                if (++__indices[__i] < __size_[__i])
-                {
-                    ++__k;
-                    __1d_[__k] = __1d_[__k-1] + __stride_[__i];
-                    for (size_t __j = __i + 1; __j != __indices.size(); ++__j)
-                        __1d_[__k] -= __stride_[__j] * (__size_[__j] - 1);
-                    break;
-                }
-                else
-                {
-                    if (__i == 0)
-                        return;
-                    __indices[__i--] = 0;
-                }
-            }
+void gslice::__init(size_t __start) {
+  valarray<size_t> __indices(__size_.size());
+  size_t __k = __size_.size() != 0;
+  for (size_t __i = 0; __i < __size_.size(); ++__i)
+    __k *= __size_[__i];
+  __1d_.resize(__k);
+  if (__1d_.size()) {
+    __k        = 0;
+    __1d_[__k] = __start;
+    while (true) {
+      size_t __i = __indices.size() - 1;
+      while (true) {
+        if (++__indices[__i] < __size_[__i]) {
+          ++__k;
+          __1d_[__k] = __1d_[__k - 1] + __stride_[__i];
+          for (size_t __j = __i + 1; __j != __indices.size(); ++__j)
+            __1d_[__k] -= __stride_[__j] * (__size_[__j] - 1);
+          break;
+        } else {
+          if (__i == 0)
+            return;
+          __indices[__i--] = 0;
         }
+      }
     }
+  }
 }
 
 _LIBCPP_END_NAMESPACE_STD