Replaced include/swift/Basic/Algorithm.h with calls to standard algorithms

LLVM now requires C++14, and the header says the algorithms are
backported from C++14.

include/swift/Basic/Algorithm.h

@@ -1,35 +0,0 @@
-//===--- Algorithm.h - ------------------------------------------*- C++ -*-===//
-//
-// This source file is part of the Swift.org open source project
-//
-// Copyright (c) 2014 - 2017 Apple Inc. and the Swift project authors
-// Licensed under Apache License v2.0 with Runtime Library Exception
-//
-// See https://swift.org/LICENSE.txt for license information
-// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
-//
-//===----------------------------------------------------------------------===//
-//
-//  This file defines helper algorithms, some of which are ported from C++14,
-//  which may not be available on all platforms yet.
-//
-//===----------------------------------------------------------------------===//
-
-#ifndef SWIFT_BASIC_ALGORITHM_H
-#define SWIFT_BASIC_ALGORITHM_H
-
-namespace swift {
-  /// Returns the minimum of `a` and `b`, or `a` if they are equivalent.
-  template <typename T>
-  constexpr const T &min(const T &a, const T &b) {
-    return !(b < a) ? a : b;
-  }
-  
-  /// Returns the maximum of `a` and `b`, or `a` if they are equivalent.
-  template <typename T>
-  constexpr const T &max(const T &a, const T &b) {
-    return (a < b) ? b : a;
-  }
-} // end namespace swift
-
-#endif // SWIFT_BASIC_ALGORITHM_H

include/swift/Basic/FlaggedPointer.h

@@ -17,13 +17,12 @@
 #ifndef SWIFT_BASIC_FLAGGEDPOINTER_H
 #define SWIFT_BASIC_FLAGGEDPOINTER_H
 
+#include <algorithm>
 #include <cassert>
 
 #include "llvm/Support/Compiler.h"
 #include "llvm/Support/PointerLikeTypeTraits.h"
 
-#include "Algorithm.h"
-
 namespace swift {
 
 /// This class implements a pair of a pointer and boolean flag.
@@ -170,7 +169,7 @@ public:
   enum {
     NumLowBitsAvailable = (BitPosition >= PtrTraits::NumLowBitsAvailable)
       ? PtrTraits::NumLowBitsAvailable
-      : (swift::min(int(BitPosition + 1),
+      : (std::min(int(BitPosition + 1),
         int(PtrTraits::NumLowBitsAvailable)) - 1)
   };
 };

include/swift/Basic/PrefixMap.h

@@ -34,7 +34,6 @@
 #ifndef SWIFT_BASIC_PREFIXMAP_H
 #define SWIFT_BASIC_PREFIXMAP_H
 
-#include "swift/Basic/Algorithm.h"
 #include "swift/Basic/Debug.h"
 #include "swift/Basic/LLVM.h"
 #include "swift/Basic/type_traits.h"
@@ -53,8 +52,8 @@ template <class KeyElementType> class PrefixMapKeyPrinter;
 /// A map whose keys are sequences of comparable values, optimized for
 /// finding a mapped value for the longest matching initial subsequence.
 template <class KeyElementType, class ValueType,
-          size_t InlineKeyCapacity
+          size_t InlineKeyCapacity = std::max(
-             = max<size_t>((sizeof(void*) - 1) / sizeof(KeyElementType), 1)>
+              (sizeof(void *) - 1) / sizeof(KeyElementType), size_t(1))>
 class PrefixMap {
 public:
   using KeyType = ArrayRef<KeyElementType>;