[libc++] Qualifies size_t.

This has been done using the following command

  find libcxx/test -type f -exec perl -pi -e 's|^([^/]+?)((?<!::)size_t)|\1std::\2|' \{} \;

And manually removed some false positives in std/depr/depr.c.headers.

The `std` module doesn't export `::size_t`, this is a preparation for that module.

Reviewed By: ldionne, #libc, EricWF, philnik

Differential Revision: https://reviews.llvm.org/D146088

libcxx/test/std/strings/basic.string/string.cons/dtor.pass.cpp

@@ -23,7 +23,7 @@ struct throwing_alloc
 {
     typedef T value_type;
     throwing_alloc(const throwing_alloc&);
-    T *allocate(size_t);
+    T *allocate(std::size_t);
     ~throwing_alloc() noexcept(false);
 };
 

libcxx/test/std/strings/basic.string/string.cons/implicit_deduction_guides.pass.cpp

@@ -81,7 +81,7 @@ TEST_CONSTEXPR_CXX20 bool test() {
   }
   { // Testing (4) w/o allocator
     const std::string sin("abc");
-    std::basic_string s(sin, (size_t)1);
+    std::basic_string s(sin, (std::size_t)1);
     ASSERT_SAME_TYPE(decltype(s), std::string);
     assert(s == "bc");
 
@@ -97,7 +97,7 @@ TEST_CONSTEXPR_CXX20 bool test() {
   }
   { // Testing (4) w/ allocator
     const std::string sin("abc");
-    std::basic_string s(sin, (size_t)1, std::allocator<char>{});
+    std::basic_string s(sin, (std::size_t)1, std::allocator<char>{});
     ASSERT_SAME_TYPE(decltype(s), std::string);
     assert(s == "bc");
 
@@ -113,7 +113,7 @@ TEST_CONSTEXPR_CXX20 bool test() {
   }
   { // Testing (5) w/o allocator
     const std::string sin("abc");
-    std::basic_string s(sin, (size_t)1, (size_t)3);
+    std::basic_string s(sin, (std::size_t)1, (size_t)3);
     ASSERT_SAME_TYPE(decltype(s), std::string);
     assert(s == "bc");
 
@@ -129,7 +129,7 @@ TEST_CONSTEXPR_CXX20 bool test() {
   }
   { // Testing (5) w/ allocator
     const std::string sin("abc");
-    std::basic_string s(sin, (size_t)1, (size_t)3, std::allocator<char>{});
+    std::basic_string s(sin, (std::size_t)1, (size_t)3, std::allocator<char>{});
     ASSERT_SAME_TYPE(decltype(s), std::string);
     assert(s == "bc");
 
@@ -144,18 +144,18 @@ TEST_CONSTEXPR_CXX20 bool test() {
 #endif
   }
   { // Testing (6) w/o allocator
-    std::basic_string s("abc", (size_t)2);
+    std::basic_string s("abc", (std::size_t)2);
     ASSERT_SAME_TYPE(decltype(s), std::string);
     assert(s == "ab");
 
 #ifndef TEST_HAS_NO_WIDE_CHARACTERS
-    std::basic_string w(L"abcdef", (size_t)3);
+    std::basic_string w(L"abcdef", (std::size_t)3);
     ASSERT_SAME_TYPE(decltype(w), std::wstring);
     assert(w == L"abc");
 #endif
   }
   { // Testing (6) w/ allocator
-    std::basic_string s("abc", (size_t)2, std::allocator<char>{});
+    std::basic_string s("abc", (std::size_t)2, std::allocator<char>{});
     ASSERT_SAME_TYPE(decltype(s), std::string);
     assert(s == "ab");
 

libcxx/test/std/strings/basic.string/string.cons/move_assign_noexcept.pass.cpp

@@ -31,7 +31,7 @@ struct some_alloc
 {
     typedef T value_type;
     some_alloc(const some_alloc&);
-    T *allocate(size_t);
+    T *allocate(std::size_t);
 };
 
 template <class T>
@@ -41,7 +41,7 @@ struct some_alloc2
 
     some_alloc2() {}
     some_alloc2(const some_alloc2&);
-    T *allocate(size_t);
+    T *allocate(std::size_t);
     void deallocate(void*, unsigned) {}
 
     typedef std::false_type propagate_on_container_move_assignment;
@@ -55,7 +55,7 @@ struct some_alloc3
 
     some_alloc3() {}
     some_alloc3(const some_alloc3&);
-    T *allocate(size_t);
+    T *allocate(std::size_t);
     void deallocate(void*, unsigned) {}
 
     typedef std::false_type propagate_on_container_move_assignment;