WinSDK: add some more constants to the overlay

The WinReg.h constants for the register hives are not imported through
the clang importer due to the complicated casting.  Duplicate the values
to allow usage in Swift.

Author: compnerd

stdlib/public/Windows/WinSDK.swift

@@ -90,6 +90,18 @@ public let DPI_AWARENESS_CONTEXT_PER_MONITOR_AWARE_V2: DPI_AWARENESS_CONTEXT =
 public let DPI_AWARENESS_CONTEXT_UNAWARE_GDISCALED: DPI_AWARENESS_CONTEXT =
     DPI_AWARENESS_CONTEXT(bitPattern: -5)!
 
+// winreg.h
+public let HKEY_CLASSES_ROOT: HKEY = HKEY(bitPattern: 0x80000000)!
+public let HKEY_CURRENT_USER: HKEY = HKEY(bitPattern: 0x80000001)!
+public let HKEY_LOCAL_MACHINE: HKEY = HKEY(bitPattern: 0x80000002)!
+public let HKEY_USERS: HKEY = HKEY(bitPattern: 0x80000003)!
+public let HKEY_PERFORMANCE_DATA: HKEY = HKEY(bitPattern: 0x80000004)!
+public let HKEY_PERFORMANCE_TEXT: HKEY = HKEY(bitPattern: 0x80000050)!
+public let HKEY_PERFORMANCE_NLSTEXT: HKEY = HKEY(bitPattern: 0x80000060)!
+public let HKEY_CURRENT_CONFIG: HKEY = HKEY(bitPattern: 0x80000005)!
+public let HKEY_DYN_DATA: HKEY = HKEY(bitPattern: 0x80000006)!
+public let HKEY_CURRENT_USER_LOCAL_SETTINGS: HKEY = HKEY(bitPattern: 0x80000007)!
+
 // Swift Convenience
 public extension FILETIME {
   var time_t: time_t {