Implement full support for non-pointer pointers in custom allocators for string. This completes the custom pointer support for the entire library.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@185167 91177308-0d34-0410-b5e6-96231b3b80d8

test/strings/basic.string/string.capacity/capacity.pass.cpp

@@ -15,6 +15,7 @@
 #include <cassert>
 
 #include "../test_allocator.h"
+#include "../min_allocator.h"
 
 template <class S>
 void
@@ -36,6 +37,7 @@ test(S s)
 
 int main()
 {
+    {
     typedef std::basic_string<char, std::char_traits<char>, test_allocator<char> > S;
     S s;
     test(s);
@@ -45,4 +47,12 @@ int main()
     s.assign(100, 'a');
     s.erase(50);
     test(s);
+    }
+#if __cplusplus >= 201103L
+    {
+    typedef std::basic_string<char, std::char_traits<char>, min_allocator<char>> S;
+    S s;
+    assert(s.capacity() > 0);
+    }
+#endif
 }