Added SDKROOT env. var.

Author: stemann

src/Runner.jl

@@ -1003,7 +1003,7 @@ function generate_compiler_wrappers!(platform::AbstractPlatform; bin_path::Abstr
         write(xcrun_path, """
               #!/bin/sh
                           
-              sdk_path=/opt/\$target/\$target/sys-root
+              sdk_path=\$SDKROOT
                           
               show_sdk_path() {
                   echo "\$1"
@@ -1017,6 +1017,10 @@ function generate_compiler_wrappers!(platform::AbstractPlatform; bin_path::Abstr
                           
               while [ \$# -gt 0 ]; do
                   case "\$1" in
+                      --sdk)
+                          sdk_path=\$2
+                          shift 2
+                          ;;
                       --show-sdk-path)
                           show_sdk_path \$sdk_path
                           shift
@@ -1286,6 +1290,7 @@ function platform_envs(platform::AbstractPlatform, src_name::AbstractString;
     if Sys.isapple(platform)
         mapping["LD"] = "/opt/bin/$(triplet(platform))/ld"
         mapping["MACOSX_DEPLOYMENT_TARGET"] = macos_version(platform)
+        mapping["SDKROOT"] = "/opt/$(triplet(platform))/$(triplet(platform))/sys-root"
     end
 
     # There is no broad agreement on what host compilers should be called,