[PrintAsObjC] Fix class properties with generic parameters. (#3092)

public static var myDictionary: [String: AnyObject]

becomes

    SWIFT_CLASS_PROPERTY(@Property (nonatomic, class, readonly, copy)
      NSDictionary<NSString *, id> * _Nonnull myDictionary;)

and the commas in the ObjC generic break the macro, just like they do with
C++ templates. Fix this by making the macro variadic.

rdar://problem/26879147
(cherry picked from commit a679aca)

Author: jrose-apple

lib/PrintAsObjC/PrintAsObjC.cpp

@@ -1796,9 +1796,9 @@ class ModuleWriter {
            "#endif\n"
            "#if !defined(SWIFT_CLASS_PROPERTY)\n"
            "# if __has_feature(objc_class_property)\n"
-           "#  define SWIFT_CLASS_PROPERTY(X) X\n"
+           "#  define SWIFT_CLASS_PROPERTY(...) __VA_ARGS__\n"
            "# else\n"
-           "#  define SWIFT_CLASS_PROPERTY(X)\n"
+           "#  define SWIFT_CLASS_PROPERTY(...)\n"
            "# endif\n"
            "#endif\n"
            "\n"

test/PrintAsObjC/classes.swift

@@ -409,6 +409,8 @@ public class NonObjCClass { }
 // CHECK-NEXT: + (void)setStaticString:(NSString * _Nonnull)value;
 // CHECK-NEXT: SWIFT_CLASS_PROPERTY(@property (nonatomic, class, readonly) double staticDouble;)
 // CHECK-NEXT: + (double)staticDouble;
+// CHECK-NEXT: SWIFT_CLASS_PROPERTY(@property (nonatomic, class, readonly, copy) NSDictionary<NSString *, NSString *> * _Nonnull staticDictionary;)
+// CHECK-NEXT: + (NSDictionary<NSString *, NSString *> * _Nonnull)staticDictionary;
 // CHECK-NEXT: @property (nonatomic, strong) Properties * _Nullable wobble;
 // CHECK-NEXT: @property (nonatomic, getter=isEnabled, setter=setIsEnabled:) BOOL enabled;
 // CHECK-NEXT: @property (nonatomic, getter=isAnimated) BOOL animated;
@@ -490,6 +492,7 @@ public class NonObjCClass { }
   static var staticDouble: Double {
     return 2.0
   }
+  static var staticDictionary: [String: String] { return [:] }
 
   @objc(wobble) var wibble: Properties?