Added build_style and cross-profiles dirs from xbps-src.

common/build_style/gnu-makefile.sh

@@ -0,0 +1,20 @@
+#
+# This helper is for templates using GNU Makefiles.
+#
+do_build() {
+	: ${make_cmd:=make}
+
+	${make_cmd} \
+		CC="$CC" CXX="$CXX" LD="$LD" AR="$AR" RANLIB="$RANLIB" \
+		CPP="$CPP" AS="$AS" OBJDUMP="$OBJDUMP" STRIP="$STRIP" \
+		${makejobs} ${make_build_args} ${make_build_target}
+}
+
+do_install() {
+	: ${make_cmd:=make}
+	: ${make_install_target:=install}
+
+	make_install_args+=" PREFIX=/usr DESTDIR=${DESTDIR}"
+
+	${make_cmd} ${make_install_args} ${make_install_target}
+}