compile_pkgs: replace separate debug variables with one generic

We in the end have only one place where we use those variables. It is
cleaner to have them specified directly by appropriate tool.

compile_pkgs

@@ -92,11 +92,7 @@ openwrt_feed
 # Technical variables
 declare -A available_commands # Set of all commands defined in this script
 mirror_updated="" # Variable signaling that mirrors were update in this run already
-# Variables set by _enable_debug function
-perl_debug=""
-sh_debug=""
-make_debug=""
-owrt_debug=""
+debug="" # set when debug on executed scripts should be enabled
 
 # OpenWRT directory for temporally data
 export TMPDIR="${build_dir}/tmp"
@@ -112,35 +108,29 @@ _git() {
 }
 
 _sh() {
-	sh $sh_debug "$@"
+	sh ${debug:+-x} "$@"
 }
 
 _perl() {
-	perl $perl_debug "$@"
+	perl ${debug:+-d:Trace} "$@"
 }
 
 _make() {
-	make $make_debug "$@"
+	make ${debug:+-d} "$@"
 }
 
 # Make for OpenWRT
 _openwrt_make() {
-	local mk=("make" -j "$BUILD_JOBS")
-	[ -z "$FORCE" ] || mk=("$src_dir/helpers/force-make" "-j" "$BULD_JOBS" "-c" "$FORCE" "-f" "V=s" "--")
-
-	local args=( "IGNORE_ERRORS=m" "BUILD_LOG=1" )
-	[ -z "$owrt_debug" ] || args+=( "$owrt_debug" )
-	[ "${#BUILD_ARGS[@]}" -eq 0 ] || args+=( "${BUILD_ARGS[@]}" )
-
-	"${mk[@]}" $make_debug "${args[@]}" "$@"
-}
+	local mk
+	if [ -z "$FORCE" ]; then
+		mk=("make" -j "$BUILD_JOBS")
+	else
+		mk=("$src_dir/helpers/force-make" "-j" "$BULD_JOBS" "-c" "$FORCE" "-f" "V=s" "--")
+	fi
 
-_enable_debug() {
-	set -x
-	perl_debug="-d:Trace"
-	make_debug="-d"
-	sh_debug="-x"
-	owrt_debug="V=s"
+	"${mk[@]}" ${debug:+-d} \
+		"IGNORE_ERRORS=m" "BUILD_LOG=1" ${debug:+V=s} "${BUILD_ARGS[@]}" \
+		"$@"
 }
 
 # Definition of avaliable commands ###############################################
@@ -585,7 +575,7 @@ while [ $# -gt 0 ]; do
 			CLONE_DEEP="y"
 			;;
 		-x)
-			_enable_debug
+			debug="y"
 			;;
 		-h|--help)
 			print_help