By adding a ctor to create fuzzer_allocator<T> from fuzzer_allocator<U>.
This mimics construcotrs of std::allocator<T>.
Without the constructors, some versions of libstdc++ can't compile
`vector<bool, fuzzer_allocator<bool>>`.
llvm-svn: 334077
template<typename T>
class fuzzer_allocator: public std::allocator<T> {
public:
+ fuzzer_allocator() = default;
+
+ template<class U>
+ fuzzer_allocator(const fuzzer_allocator<U>&) {}
+
template<class Other>
struct rebind { typedef fuzzer_allocator<Other> other; };
};