dockerfile: llvm needed on debian for cross comp

Signed-off-by: CrazyMax <crazy-max@users.noreply.github.com>

scripts/build/.variables

@@ -86,6 +86,12 @@ if [ "$CGO_ENABLED" = "1" ] && [ "$GO_LINKMODE" = "static" ]; then
     GO_BUILDTAGS="$GO_BUILDTAGS osusergo"
 fi
 if [ -n "$GO_STRIP" ]; then
+    # if stripping enabled and building with llvm < 12 against darwin/amd64
+    # platform, it will fail with:
+    #  # github.com/docker/cli/cmd/docker
+    #  /usr/local/go/pkg/tool/linux_amd64/link: /usr/local/go/pkg/tool/linux_amd64/link: running strip failed: exit status 1
+    #  llvm-strip: error: unsupported load command (cmd=0x5)
+    # more info: https://github.com/docker/cli/pull/3717
     GO_LDFLAGS="$GO_LDFLAGS -s -w"
 fi
 export GO_LDFLAGS="$GO_LDFLAGS" # https://github.com/koalaman/shellcheck/issues/2064