package/librelp: needs threads

Fixes:
 - http://autobuild.buildroot.org/results/e09f6eb989388cec2dab06391a8b6580aa0ff118

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

package/librelp/Config.in

@@ -1,6 +1,10 @@
 config BR2_PACKAGE_LIBRELP
 	bool "librelp"
+	depends on BR2_TOOLCHAIN_HAS_THREADS
 	help
 	  Reliable Event Logging Protocol library
 
 	  https://www.rsyslog.com/librelp/
+
+comment "librelp needs a toolchain w/ threads"
+	depends on !BR2_TOOLCHAIN_HAS_THREADS