Base: implement KnownLocations for android

Add support for android to KnownLocations.  Assume that only current
user is supported as all applications in android are isolated and single
user.  For now, place all files in ~/Apple/Library/Preferences.  This is
the last piece needed in CoreFoundation for Android support.

Author: compnerd

CoreFoundation/Base.subproj/CFKnownLocations.c

@@ -91,6 +91,20 @@ CFURLRef _Nullable _CFKnownLocationCreatePreferencesURLForUser(CFKnownLocationUs
             break;
     }
 
+#elif TARGET_OS_ANDROID
+
+    switch (user) {
+    case _kCFKnownLocationUserAny:
+    case _kCFKnownLocationUserByName:
+      abort();
+    case _kCFKnownLocationUserCurrent: {
+      CFURLRef home = CFCopyHomeDirectoryURLForUser(CFGetUserName());
+      location = CFURLCreateWithFileSystemPathRelativeToBase(kCFAllocatorSystemDefault, CFSTR("/Apple/Library/Preferences"), kCFURLPOSIXPathStyle, true, home);
+      CFRelease(home);
+      break;
+    }
+    }
+
 #else
 
     #error For this platform, you need to define a preferences path for both 'any user' (i.e. installation-wide preferences) or the current user.