ext-toolchain-wrapper: force hash-style to 'both'

If ext-toolchain-wrapper was built with a gcc that uses hash-style 'gnu' by
default, the resulting binary might be unusable on other systems. The error
in this case is "Floating point exception".
Using hash-style 'both' solves this issue.

Signed-off-by: Patrick Ziegler <patrick.ziegler@fh-kl.de>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>

toolchain/toolchain-external/ext-tool.mk

@@ -491,7 +491,9 @@ $(HOST_DIR)/usr/bin/ext-toolchain-wrapper: $(STAMP_DIR)/ext-toolchain-installed
 			;; \
 		esac; \
 	done ;
-	$(HOSTCC) $(HOST_CFLAGS) $(TOOLCHAIN_EXTERNAL_WRAPPER_ARGS) -s \
+	# We use --hash-style=both to increase the compatibility of
+	# the generated binary with older platforms
+	$(HOSTCC) $(HOST_CFLAGS) $(TOOLCHAIN_EXTERNAL_WRAPPER_ARGS) -s -Wl,--hash-style=both \
 		toolchain/toolchain-external/ext-toolchain-wrapper.c -o $@
 
 # 'uclibc' is the target to provide toolchain / staging dir