toolchain/helpers.mk: don't discard check_arm_abi stderr

Since we only need to know whether the compiler runs successfully, and
stderr is empty for the success case, there is no need to redirect stderr to
/dev/null. Moreover, stderr output of the failing case reveals valuable
information on the real failure reason.

Cc: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Acked-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

toolchain/helpers.mk

@@ -297,7 +297,7 @@ check_arm_abi = \
 		echo "External toolchain uses the unsuported OABI" ; \
 		exit 1 ; \
 	fi ; \
-	if ! echo 'int main(void) {}' | $${__CROSS_CC} -x c -o /dev/null - 2>/dev/null; then \
+	if ! echo 'int main(void) {}' | $${__CROSS_CC} -x c -o /dev/null - ; then \
 		abistr_$(BR2_ARM_EABI)='EABI'; \
 		abistr_$(BR2_ARM_EABIHF)='EABIhf'; \
 		echo "Incorrect ABI setting: $${abistr_y} selected, but toolchain is incompatible"; \