buildroot toolchain fix for make 4.3+

patch.diff

diff --git a/toolchain/helpers.mk b/toolchain/helpers.mk
index 996cc70d44..8cd12f8a61 100644
--- a/toolchain/helpers.mk
+++ b/toolchain/helpers.mk
@@ -122,9 +122,9 @@ copy_toolchain_sysroot = \
 		if [ "$${target}" == "$${target\#/}" ] ; then \
 			continue ; \
 		fi ; \
-		relpath="$(call relpath_prefix,$${target\#/})" ; \
+		relpath="$(call relpath_prefix,$${target$(NUM_CHAR)/})" ; \
 		echo "Fixing symlink $${link} from $${target} to $${relpath}$${target\#/}" ; \
-		ln -sf $${relpath}$${target\#/} $${link} ; \
+		ln -sf $${relpath}$${target$(NUM_CHAR)/} $${link} ; \
 	done ; \
 	relpath="$(call relpath_prefix,$${ARCH_LIB_DIR})" ; \
 	if [ "$${relpath}" != "" ]; then \
diff --git a/toolchain/toolchain-external/pkg-toolchain-external.mk b/toolchain/toolchain-external/pkg-toolchain-external.mk
index 1c43409514..2362defe8c 100644
--- a/toolchain/toolchain-external/pkg-toolchain-external.mk
+++ b/toolchain/toolchain-external/pkg-toolchain-external.mk
@@ -109,6 +109,20 @@ define TOOLCHAIN_EXTERNAL_MOVE
 endef
 endif
 
+# make 4.3:
+# https://lwn.net/Articles/810071/
+# Number signs (#) appearing inside a macro reference or function invocation
+#   no longer introduce comments and should not be escaped with backslashes:
+#   thus a call such as:
+#     foo := $(shell echo '#')
+#   is legal.  Previously the number sign needed to be escaped, for example:
+#     foo := $(shell echo '\#')
+#   Now this latter will resolve to "\#".  If you want to write makefiles
+#   portable to both versions, assign the number sign to a variable:
+#     H := \#
+#     foo := $(shell echo '$H')
+NUM_CHAR := \#
+
 #
 # Definitions of the list of libraries that should be copied to the target.
 #