Drop 10.5 support

compat/mac/AvailabilityMacros.h

 // Copyright 2014 The Crashpad Authors. All rights reserved.
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
 //
 //     http://www.apache.org/licenses/LICENSE-2.0
 //
 // Unless required by applicable law or agreed to in writing, software
 // distributed under the License is distributed on an "AS IS" BASIS,
 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
 #ifndef CRASHPAD_COMPAT_MAC_AVAILABILITYMACROS_H_
 #define CRASHPAD_COMPAT_MAC_AVAILABILITYMACROS_H_
 
 #include_next <AvailabilityMacros.h>
 
-// 10.6 SDK
-
-#ifndef MAC_OS_X_VERSION_10_6
-#define MAC_OS_X_VERSION_10_6 1060
-#endif
-
 // 10.7 SDK
 
 #ifndef MAC_OS_X_VERSION_10_7
 #define MAC_OS_X_VERSION_10_7 1070
 #endif
 
 // 10.8 SDK
 
 #ifndef MAC_OS_X_VERSION_10_8
 #define MAC_OS_X_VERSION_10_8 1080
 #endif
 
 // 10.9 SDK
 
 #ifndef MAC_OS_X_VERSION_10_9
 #define MAC_OS_X_VERSION_10_9 1090
 #endif
 
 // 10.10 SDK
 
 #ifndef MAC_OS_X_VERSION_10_10
 #define MAC_OS_X_VERSION_10_10 101000
 #endif
 
 #endif  // CRASHPAD_COMPAT_MAC_AVAILABILITYMACROS_H_