package/open62541: force Release build

Force Release build to remove -Werror and avoid the following build
failure:

/home/giuliobenetti/autobuild/run/instance-3/output-1/build/open62541-1.0/arch/network_tcp.c: At top level:
cc1: error: unrecognized command line option '-Wno-static-in-inline' [-Werror]
cc1: all warnings being treated as errors

Fixes:
 - http://autobuild.buildroot.org/results/24b429ce0ae2b33e72bb6a0f523c3906e539a4fd

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/open62541/open62541.mk

@@ -13,9 +13,11 @@ OPEN62541_INSTALL_STAGING = YES
 OPEN62541_LICENSE = MPL-2.0
 OPEN62541_LICENSE_FILES = LICENSE
 
+# Force Release build to remove -Werror.
 # Don't use git describe to get the version number.
 # Disable hardening options to let Buildroot handle it.
 OPEN62541_CONF_OPTS = \
+	-DCMAKE_BUILD_TYPE=Release \
 	-DGIT_EXECUTABLE=NO \
 	-DOPEN62541_VERSION=$(OPEN62541_VERSION) \
 	-DUA_ENABLE_HARDENING=OFF