xerces: enable threads if available

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Reviewed-by: Matt Weber <matthew.weber@rockwellcollins.com>
Reviewed-by: Matt Weber &lt;<a href="mailto:matthew.weber@rockwellcollins.com" target="_blank">matthew.weber@rockwellcollins.com</a>&gt;<br>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

package/xerces/xerces.mk

@@ -10,9 +10,7 @@ XERCES_SITE = http://archive.apache.org/dist/xerces/c/3/sources
 XERCES_LICENSE = Apache-2.0
 XERCES_LICENSE_FILES = LICENSE
 XERCES_INSTALL_STAGING = YES
-XERCES_CONF_OPTS = \
-	--disable-threads \
-	--with-gnu-ld
+XERCES_CONF_OPTS = --with-gnu-ld
 
 define XERCES_DISABLE_SAMPLES
 	$(SED) 's/ samples//' $(@D)/Makefile.in
@@ -39,4 +37,10 @@ else
 XERCES_CONF_OPTS += --disable-network
 endif
 
+ifeq ($(BR2_TOOLCHAIN_HAS_THREADS),y)
+XERCES_CONF_OPTS += --enable-threads
+else
+XERCES_CONF_OPTS += --disable-threads
+endif
+
 $(eval $(autotools-package))