build(amu): introduce `amu.mk`
This change introduces the `amu.mk` Makefile, used to remove the need
to manually include AMU sources into the various build images.
Makefiles requiring the list of AMU sources are expected to include
this file and use `${AMU_SOURCES}` to retrieve them.
Change-Id: I3d174033ecdce6439a110d776f0c064c67abcfe0
Signed-off-by: Chris Kay <chris.kay@arm.com>
diff --git a/lib/extensions/amu/amu.mk b/lib/extensions/amu/amu.mk
new file mode 100644
index 0000000..b4e04dd
--- /dev/null
+++ b/lib/extensions/amu/amu.mk
@@ -0,0 +1,8 @@
+#
+# Copyright (c) 2021, Arm Limited. All rights reserved.
+#
+# SPDX-License-Identifier: BSD-3-Clause
+#
+
+AMU_SOURCES := lib/extensions/amu/${ARCH}/amu.c \
+ lib/extensions/amu/${ARCH}/amu_helpers.S