package/libodb-mysql: fix build with gcc 11

Fixes:
http://autobuild.buildroot.net/results/8f0/8f0e3b604ff9809e3b415036b8d99521db33c4db
http://autobuild.buildroot.net/results/d03/d038b79e719c37a93d635c6b61443033094d8716

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>

package/libodb-mysql/libodb-mysql.mk

@@ -12,6 +12,8 @@ LIBODB_MYSQL_INSTALL_STAGING = YES
 LIBODB_MYSQL_LICENSE = GPL-2.0
 LIBODB_MYSQL_LICENSE_FILES = LICENSE
 LIBODB_MYSQL_DEPENDENCIES = libodb mysql
-LIBODB_MYSQL_CONF_ENV = LIBS=`$(STAGING_DIR)/usr/bin/mysql_config --libs`
+LIBODB_MYSQL_CONF_ENV = \
+	CXXFLAGS="$(TARGET_CXXFLAGS) -std=c++11" \
+	LIBS=`$(STAGING_DIR)/usr/bin/mysql_config --libs`
 
 $(eval $(autotools-package))