Update Kelvin flag for bintuils 2.40

Silence the loadable segment RWX warning.

Change-Id: I6973be722149e47f5e43faedf2cbe763129686ce

rules/matcha.bzl

diff --git a/rules/matcha.bzl b/rules/matcha.bzl
index 87b4594..c8886e6 100644
--- a/rules/matcha.bzl
+++ b/rules/matcha.bzl
@@ -568,6 +568,8 @@
         linking_contexts = linking_contexts,
         user_link_flags = ctx.attr.linkopts + [
             "-Wl,-T,{}".format(ctx.file.linker_script.path),
+            # binutils >= 2.39 checks the loadable segments RWX setting by default.
+            "-Wl,--no-warn-rwx-segments",
         ],
         additional_inputs = depset([ctx.file.linker_script] + ctx.files.linker_script_includes),
         output_type = "executable",