Merge pull request swiftlang#4878 from kateinoigakukun/pr-9a7128f36562ce5da5c7f523fd6d207e4bf575e1

Author: kateinoigakukun

CoreFoundation/Base.subproj/CFPlatform.c

@@ -1627,7 +1627,7 @@ CF_PRIVATE int asprintf(char **ret, const char *format, ...) {
 #if DEPLOYMENT_RUNTIME_SWIFT
 #include <fcntl.h>
 
-extern void swift_retain(void *);
+extern void *swift_retain(void *);
 extern void swift_release(void *);
 
 #if SWIFT_CORELIBS_FOUNDATION_HAS_THREADS

CoreFoundation/Base.subproj/CFRuntime.c

@@ -1411,7 +1411,7 @@ int DllMain( HINSTANCE hInstance, DWORD dwReason, LPVOID pReserved ) {
 #endif
 
 #if DEPLOYMENT_RUNTIME_SWIFT
-extern void swift_retain(void *);
+extern void *swift_retain(void *);
 #endif
 
 // For "tryR==true", a return of NULL means "failed".