[Runner] Updated xcrun executable to handle --sdk, --show-sdk-path and --show-sdk-version.

Also, added SDKROOT env. var.

Author: stemann

src/Runner.jl

@@ -999,10 +999,46 @@ function generate_compiler_wrappers!(platform::AbstractPlatform; bin_path::Abstr
         # `xcrun` is another macOS-specific tool, which is occasionally needed to run some
         # commands, for example for the CGO linker.  Ref:
         # <https://github.com/JuliaPackaging/Yggdrasil/pull/2962>.
+        # Cf. <https://www.unix.com/man-page/osx/1/xcrun/>
         xcrun_path = joinpath(bin_path, triplet(platform), "xcrun")
         write(xcrun_path, """
               #!/bin/sh
-              exec "\${@}"
+                          
+              sdk_path=\$SDKROOT
+                          
+              show_sdk_path() {
+                  echo "\$1"
+              }
+                          
+              show_sdk_version() {
+                  grep -A1 '<key>Version</key>' \$1/SDKSettings.plist \
+                  | tail -n1 \
+                  | sed -E -e 's/\\s*<string>([^<]+)<\\/string>\\s*/\\1/'
+              }
+                          
+              while [ \$# -gt 0 ]; do
+                  case "\$1" in
+                      --sdk)
+                          sdk_path=\$2
+                          shift 2
+                          ;;
+                      --show-sdk-path)
+                          show_sdk_path \$sdk_path
+                          shift
+                          ;;
+                      --show-sdk-version)
+                          show_sdk_version \$sdk_path
+                          shift
+                          ;;
+                      *)
+                          break
+                          ;;
+                  esac
+              done
+              
+              if [ \$# -gt 0 ]; then
+                "\$@"
+              fi
               """)
         chmod(xcrun_path, 0o775)
     end
@@ -1255,6 +1291,7 @@ function platform_envs(platform::AbstractPlatform, src_name::AbstractString;
     if Sys.isapple(platform)
         mapping["LD"] = "/opt/bin/$(triplet(platform))/ld"
         mapping["MACOSX_DEPLOYMENT_TARGET"] = macos_version(platform)
+        mapping["SDKROOT"] = "/opt/$(aatriplet(platform))/$(aatriplet(platform))/sys-root"
     end
 
     # There is no broad agreement on what host compilers should be called,