Merge topic 'osx-find-sdk-for-deployment-target'

bf5a5bc bootstrap: Do not suppress CMAKE_OSX_SYSROOT if CFLAGS have -isysroot (#14324)
95f78e0 OS X: Search for SDK based on deployment target (#14324)

Modules/Platform/Darwin.cmake

@@ -132,7 +132,11 @@ elseif("${CMAKE_GENERATOR}" MATCHES Xcode
     # specially named SDKs.
     set(_CMAKE_OSX_SDKS_VER_SUFFIX_10.4 "u")
     set(_CMAKE_OSX_SDKS_VER_SUFFIX_10.3 ".9")
-    set(_CMAKE_OSX_SDKS_VER ${_CURRENT_OSX_VERSION}${_CMAKE_OSX_SDKS_VER_SUFFIX_${_CURRENT_OSX_VERSION}})
+    if(CMAKE_OSX_DEPLOYMENT_TARGET)
+      set(_CMAKE_OSX_SDKS_VER ${CMAKE_OSX_DEPLOYMENT_TARGET}${_CMAKE_OSX_SDKS_VER_SUFFIX_${CMAKE_OSX_DEPLOYMENT_TARGET}})
+    else()
+      set(_CMAKE_OSX_SDKS_VER ${_CURRENT_OSX_VERSION}${_CMAKE_OSX_SDKS_VER_SUFFIX_${_CURRENT_OSX_VERSION}})
+    endif()
     set(_CMAKE_OSX_SYSROOT_DEFAULT
       "${_CMAKE_OSX_SDKS_DIR}/MacOSX${_CMAKE_OSX_SDKS_VER}.sdk")
   else()

bootstrap

@@ -1525,14 +1525,6 @@ set (CMAKE_MAN_DIR "'"${cmake_man_dir}"'" CACHE PATH "Install location for man p
 set (CMAKE_DATA_DIR "'"${cmake_data_dir}"'" CACHE PATH "Install location for data (relative to prefix)." FORCE)
 ' > "${cmake_bootstrap_dir}/InitialCacheFlags.cmake"
 
-# Suppress -isysroot if user-provided flags already have it.
-if echo "${cmake_c_flags}"   | grep isysroot >/dev/null 2>&1 &&
-   echo "${cmake_cxx_flags}" | grep isysroot >/dev/null 2>&1; then
-  echo '
-set(CMAKE_OSX_SYSROOT "" CACHE PATH "" FORCE)
-' >> "${cmake_bootstrap_dir}/InitialCacheFlags.cmake"
-fi
-
 # Add configuration settings given as command-line options.
 if [ "x${cmake_bootstrap_qt_gui}" != "x" ]; then
   echo '