build-system: load required overlays for building a module

Pmodules/libpbuild.bash

@@ -946,12 +946,14 @@ readonly -f pbuild.build_module_legacy
 
 declare -n Config
 declare -a Systems
+declare -a UseOverlays
 pbuild.build_module_yaml(){
 	local -- module_name="$1"
 	local -- module_version="$2"
 	Config="$3"
 	local -- module_relstage="${Config['relstage']}"
 	readarray -t Systems <<< "${Config['systems']}"
+	readarray -t UseOverlays <<< "${Config['use_overlays']}"
 	shift 3
 	_build_module "${module_name}" "${module_version}" "${module_relstage}" "$@"
 }
@@ -983,6 +985,10 @@ _build_module() {
 		[[ :${LOADEDMODULES}: =~ :$1: ]]
 	}
 
+	load_overlays(){
+		eval "$( "${modulecmd}" bash use "${Config['use_overlays']}" )"
+	}
+
 	#......................................................................
 	#
 	# Load build- and run-time dependencies.

Pmodules/modbuild.in

@@ -535,6 +535,7 @@ declare -A Yaml_default_config=(
 	['sub_packages']=''		# !!map
 	['target_cpus']=''		# !!seq of strings
 	['urls']=''			# !!map
+	['use_overlays']=''		# !!seq
 	['variant']=''			# !!str
 )
 
@@ -679,7 +680,7 @@ build_modules_yaml_v1(){
 					pm::get_value "${yaml_input}" value "${key}" '!!seq'
 					cfg[${key,,}]="${value}"
 					;;
-				build_requires|configure_args|docfiles|patch_files|runtime_deps|systems|variant )
+				build_requires|configure_args|docfiles|patch_files|runtime_deps|systems|use_overlays|variant )
 					pm::get_seq "${yaml_input}" value "${key}"
 					cfg[${key,,}]="${value}"
 					;;