rust: Add proc_macro NOTICE files

Collect NOTICE files from proc-macros in a similar fashion to static
libraries.

Test: m
Change-Id: Id8ef8d74c8e0ea6ce3c137231b41addcb763876d
diff --git a/core/soong_cc_rust_prebuilt.mk b/core/soong_cc_rust_prebuilt.mk
index 7a177ff..07e577a 100644
--- a/core/soong_cc_rust_prebuilt.mk
+++ b/core/soong_cc_rust_prebuilt.mk
@@ -260,6 +260,9 @@
 installed_static_library_notice_file_targets += \
     $(foreach lib,$(LOCAL_RLIB_LIBRARIES), \
       NOTICE-$(if $(LOCAL_IS_HOST_MODULE),HOST$(if $(my_host_cross),_CROSS,),TARGET)-RLIB_LIBRARIES-$(lib))
+installed_static_library_notice_file_targets += \
+    $(foreach lib,$(LOCAL_PROC_MACRO_LIBRARIES), \
+      NOTICE-$(if $(LOCAL_IS_HOST_MODULE),HOST$(if $(my_host_cross),_CROSS,),TARGET)-PROC_MACRO_LIBRARIES-$(lib))
 
 $(notice_target): | $(installed_static_library_notice_file_targets)
 $(LOCAL_INSTALLED_MODULE): | $(notice_target)