Add objc_compile to DEFAULT_SYSROOT_ACTIONS

Copybara Import from https://github.com/bazelbuild/rules_cc/pull/607

BEGIN_PUBLIC
Add objc_compile to DEFAULT_SYSROOT_ACTIONS (#607)

When cross compiling objc, it is necessary to be able to pass `--sysroot` to `objc_compile` actions.

Closes #607
END_PUBLIC

COPYBARA_INTEGRATE_REVIEW=https://github.com/bazelbuild/rules_cc/pull/607 from cerisier:objc_sysroot 527806f3df7391e9a643f78258b34627c951babe
PiperOrigin-RevId: 874892922
Change-Id: I8e503e8d4842b041957f18d0a39d08ad95bc72b5

cc/toolchains/args/sysroot.bzl

diff --git a/cc/toolchains/args/sysroot.bzl b/cc/toolchains/args/sysroot.bzl
index 20e0af4..98c99f7 100644
--- a/cc/toolchains/args/sysroot.bzl
+++ b/cc/toolchains/args/sysroot.bzl
@@ -20,6 +20,7 @@
 _DEFAULT_SYSROOT_ACTIONS = [
     Label("//cc/toolchains/actions:assembly_actions"),
     Label("//cc/toolchains/actions:c_compile"),
+    Label("//cc/toolchains/actions:objc_compile"),
     Label("//cc/toolchains/actions:cpp_compile_actions"),
     Label("//cc/toolchains/actions:link_actions"),
 ]