require_macos_sdk: suppress harmless tar warnings (#12619)

Otherwise for some of the SDK tarballs (e.g. the 14.0 one) the log
is flooded with these warnings which are caused by BSD tar creating
the archive and GNU tar extracting it.

Author: fingolfin

platforms/macos_sdks.jl

@@ -112,10 +112,14 @@ function get_macos_sdk_script(version::String; deployment_target::String = versi
         echo "Extracting MacOSX${macos_sdk_version}.sdk.tar.xz (this may take a while)"
         rm -rf /opt/${target}/${target}/sys-root/System
         rm -rf /opt/${target}/${target}/sys-root/usr/include/libxml2/libxml
+        # extract the tarball into the sys-root so all compilers pick it up
+        # automatically, and use --warning=no-unknown-keyword to hide harmless
+        # warnings about unsupported pax header keywords like "SCHILY.fflags"
         tar --extract \
             --file=${WORKSPACE}/srcdir/MacOSX${macos_sdk_version}.sdk.tar.xz \
             --directory="/opt/${target}/${target}/sys-root/." \
             --strip-components=1 \
+            --warning=no-unknown-keyword \
             MacOSX${macos_sdk_version}.sdk/System \
             MacOSX${macos_sdk_version}.sdk/usr
         export MACOSX_DEPLOYMENT_TARGET=${macosx_deployment_target}