[libc] remove BlockStore from cpp namespace (#85312)

The cpp namespace should only be used to mirror APIs from C++'s std::
namespace
(at least until we share more code with libc++, see

https://discourse.llvm.org/t/rfc-project-hand-in-hand-llvm-libc-libc-code-sharing/77701)

libc/src/__support/blockstore.h

@@ -16,7 +16,6 @@
 #include <stdint.h>
 
 namespace LIBC_NAMESPACE {
-namespace cpp {
 
 // The difference between BlockStore a traditional vector types is that,
 // when more capacity is desired, a new block is added instead of allocating
@@ -203,7 +202,6 @@ void BlockStore<T, BLOCK_SIZE, REVERSE_ORDER>::destroy(
 template <typename T, size_t BLOCK_SIZE>
 using ReverseOrderBlockStore = BlockStore<T, BLOCK_SIZE, true>;
 
-} // namespace cpp
 } // namespace LIBC_NAMESPACE
 
 #endif // LLVM_LIBC_SRC___SUPPORT_BLOCKSTORE_H

libc/src/stdlib/atexit.cpp

@@ -36,7 +36,7 @@ struct AtExitUnit {
 //        mutexes simply passthrough. We will need a lock free stack.
 using ExitCallbackList = FixedVector<AtExitUnit, 64>;
 #elif defined(LIBC_COPT_PUBLIC_PACKAGING)
-using ExitCallbackList = cpp::ReverseOrderBlockStore<AtExitUnit, 32>;
+using ExitCallbackList = ReverseOrderBlockStore<AtExitUnit, 32>;
 #else
 // BlockStore uses dynamic memory allocation. To avoid dynamic memory
 // allocation in tests, we use a fixed size callback list when built for

libc/test/src/__support/blockstore_test.cpp

@@ -19,7 +19,7 @@ class LlvmLibcBlockStoreTest : public LIBC_NAMESPACE::testing::Test {
 public:
   template <size_t BLOCK_SIZE, size_t ELEMENT_COUNT, bool REVERSE>
   void populate_and_iterate() {
-    LIBC_NAMESPACE::cpp::BlockStore<Element, BLOCK_SIZE, REVERSE> block_store;
+    LIBC_NAMESPACE::BlockStore<Element, BLOCK_SIZE, REVERSE> block_store;
     for (int i = 0; i < int(ELEMENT_COUNT); ++i)
       ASSERT_TRUE(block_store.push_back({i, 2 * i, 3 * unsigned(i)}));
     auto end = block_store.end();
@@ -38,12 +38,12 @@ class LlvmLibcBlockStoreTest : public LIBC_NAMESPACE::testing::Test {
       }
     }
     ASSERT_EQ(i, int(ELEMENT_COUNT));
-    LIBC_NAMESPACE::cpp::BlockStore<Element, BLOCK_SIZE, REVERSE>::destroy(
+    LIBC_NAMESPACE::BlockStore<Element, BLOCK_SIZE, REVERSE>::destroy(
         &block_store);
   }
 
   template <bool REVERSE> void back_test() {
-    using LIBC_NAMESPACE::cpp::BlockStore;
+    using LIBC_NAMESPACE::BlockStore;
     BlockStore<int, 4, REVERSE> block_store;
     for (int i = 0; i < 20; i++)
       ASSERT_TRUE(block_store.push_back(i));
@@ -53,7 +53,7 @@ class LlvmLibcBlockStoreTest : public LIBC_NAMESPACE::testing::Test {
   }
 
   template <bool REVERSE> void empty_test() {
-    using LIBC_NAMESPACE::cpp::BlockStore;
+    using LIBC_NAMESPACE::BlockStore;
     BlockStore<int, 2, REVERSE> block_store;
 
     ASSERT_TRUE(block_store.empty());