Make sure that the sanitizers use the same minimum OS X deployment target as llvm/clang/swift.

Otherwise, we run into an issue with certain clangs and linking in libc++. libc++
in certain clangs require a minimum deployment target of at least 10.7.

I have not investigated further since I am trying to make progress on the
branching scheme.

rdar://26081474
(cherry picked from commit 2a27443f3ee63cc55e952e4cfb43c24661c4b7ca)

utils/build-script-impl

@@ -531,6 +531,7 @@ function set_deployment_target_based_options() {
                 -DCOMPILER_RT_ENABLE_IOS:BOOL=FALSE
                 -DCOMPILER_RT_ENABLE_WATCHOS:BOOL=FALSE
                 -DCOMPILER_RT_ENABLE_TVOS:BOOL=FALSE
+                -DSANITIZER_MIN_OSX_VERSION="${cmake_osx_deployment_target}"
             )
             if [[ $(true_false "${LLVM_ENABLE_LTO}") = "TRUE" ]]; then
                 if [[ $(cmake_needs_to_specify_standard_computed_defaults) = "TRUE" ]]; then