include: autotools.mk: do not fail in patch-libtool fixup if patch is already applied

SVN-Revision: 28419

include/autotools.mk

@@ -56,7 +56,7 @@ define patch_libtool
 			lt_version="$$$$($$(STAGING_DIR_HOST)/bin/sed -ne 's,^[[:space:]]*VERSION=\([0-9]\.[0-9]\+\).*,\1,p' $$$$lt)"; \
 			case "$$$$lt_version" in \
 				1.5|2.2|2.4) echo "autotools.mk: Found libtool v$$$$lt_version - applying patch to $$$$lt"; \
-					(cd $$$$(dirname $$$$lt) && $$(PATCH) -s -p1 < $$(TOPDIR)/tools/libtool/files/libtool-v$$$$lt_version.patch) ;; \
+					(cd $$$$(dirname $$$$lt) && $$(PATCH) -N -s -p1 < $$(TOPDIR)/tools/libtool/files/libtool-v$$$$lt_version.patch || true) ;; \
 				*) echo "autotools.mk: error: Unsupported libtool version v$$$$lt_version - cannot patch $$$$lt"; exit 1 ;; \
 			esac; \
 		done; \