[sanitizer] Max out allowed macOS deployment targets to 10.9

It's not a good idea to build the sanitizers with e.g. -DCMAKE_OSX_DEPLOYMENT_TARGET=10.12, because some deprecated functions that we intercept will cause build errors. Let's limit the allowed deployment targets to 10.9 (which is the default anyway), and warn when it's set above.

Differential Revision: https://reviews.llvm.org/D26557

llvm-svn: 286859

Author: kubamracek

compiler-rt/cmake/config-ix.cmake

@@ -217,7 +217,11 @@ if(APPLE)
       set(SANITIZER_MIN_OSX_VERSION 10.9)
     endif()
     if(SANITIZER_MIN_OSX_VERSION VERSION_LESS "10.7")
-      message(FATAL_ERROR "Too old OS X version: ${SANITIZER_MIN_OSX_VERSION}")
+      message(FATAL_ERROR "macOS deployment target '${SANITIZER_MIN_OSX_VERSION}' is too old.")
+    endif()
+    if(SANITIZER_MIN_OSX_VERSION VERSION_GREATER "10.9")
+      message(WARNING "macOS deployment target '${SANITIZER_MIN_OSX_VERSION}' is too new, setting to '10.9' instead.")
+      set(SANITIZER_MIN_OSX_VERSION 10.9)
     endif()
   endif()