Remove usage of deprecated ObjCProvider attributes (#75)

These APIs were deprecated a while ago, but Bazel 4.0.0 has removed them completely. The information in `ObjCProvider` has been migrated to `CcCompilationContext`: bazelbuild/bazel#10674

I've replaced the usages of the deprecated APIs with the equivalents from `CcCompilationContext` and can confirm that it now works with Bazel 4.0.0.

aspects.bzl

@@ -214,13 +214,9 @@ def _objc_compiler_info(ctx, target, srcs, feature_configuration, cc_toolchain):
         ),
     )
 
-    defines = ["-D\"{}\"".format(val) for val in target.objc.define.to_list()]
-    includes = ["-I{}".format(val) for val in target.objc.include.to_list()]
-    system_includes = ["-isystem {}".format(val) for val in target.objc.include_system.to_list()]
-    iquotes = ["-iquote {}".format(val) for val in target.objc.iquote.to_list()]
     frameworks = (["-F {}/..".format(val) for val in target.objc.static_framework_paths.to_list()] +
                   ["-F {}/..".format(val) for val in target.objc.dynamic_framework_paths.to_list()] +
-                  ["-F {}/..".format(val) for val in target.objc.framework_search_path_only.to_list()])
+                  ["-F {}/..".format(val) for val in target[CcInfo].compilation_context.framework_includes.to_list()])
 
     xcode_config = ctx.attr._xcode_config[apple_common.XcodeVersionConfig]
 
@@ -239,10 +235,7 @@ def _objc_compiler_info(ctx, target, srcs, feature_configuration, cc_toolchain):
                      ["-F {}/Developer/Library/Frameworks".format(platform_root)] +
                      # FIXME this needs to be done per-file to be fully correct
                      ["-fobjc-arc"] +
-                     defines +
-                     includes +
-                     iquotes +
-                     system_includes +
+                     get_compile_flags(target) +
                      frameworks +
                      (ctx.rule.attr.copts if "copts" in dir(ctx.rule.attr) else []))
 
@@ -386,5 +379,5 @@ _compilation_database = rule(
 def compilation_database(**kwargs):
     _compilation_database(
         filename = kwargs.pop("filename", "compile_commands.json"),
-        **kwargs,
+        **kwargs
     )