package/xml-security-c: needs threads

Add threads dependency to avoid the following build failure raised since
bump to version 2.0.4 in commit
27d08083ed4db5bd055219574cc602aaf8053a49:

configure: error: unable to find pthreads, currently this is required

Fixes:
 - http://autobuild.buildroot.org/results/b6065efaa722f2da911c7cf150d446da621e8c71

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

package/xml-security-c/Config.in

@@ -4,6 +4,7 @@ config BR2_PACKAGE_XML_SECURITY_C
 	depends on !BR2_STATIC_LIBS # xerces
 	depends on BR2_USE_WCHAR # xerces
 	depends on BR2_TOOLCHAIN_GCC_AT_LEAST_4_7 # C++11
+	depends	on BR2_TOOLCHAIN_HAS_THREADS
 	select BR2_PACKAGE_LIBOPENSSL_ENABLE_DES if BR2_PACKAGE_LIBOPENSSL
 	select BR2_PACKAGE_OPENSSL
 	select BR2_PACKAGE_XERCES
@@ -13,6 +14,7 @@ config BR2_PACKAGE_XML_SECURITY_C
 
 	  https://santuario.apache.org/cindex.html
 
-comment "xml-security-c needs a toolchain w/ C++, wchar, dynamic library, gcc >= 4.7"
+comment "xml-security-c needs a toolchain w/ C++, wchar, dynamic library, threads, gcc >= 4.7"
 	depends on !BR2_INSTALL_LIBSTDCPP || !BR2_USE_WCHAR || \
-		BR2_STATIC_LIBS || !BR2_TOOLCHAIN_GCC_AT_LEAST_4_7
+		BR2_STATIC_LIBS || !BR2_TOOLCHAIN_GCC_AT_LEAST_4_7 || \
+		!BR2_TOOLCHAIN_HAS_THREADS