package/mbuffer: needs threads

mbuffer unconditionally uses pthread.h and semaphore.h

Fixes:
 - http://autobuild.buildroot.org/results/2b2be32fac82f3b291f1304f977655ff8adc286a

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>

package/mbuffer/Config.in

@@ -1,11 +1,12 @@
 config BR2_PACKAGE_MBUFFER
 	bool "mbuffer"
 	depends on !BR2_STATIC_LIBS # dlopen()
+	depends on BR2_TOOLCHAIN_HAS_THREADS
 	help
 	  mbuffer is a tool for buffering data streams with a large set
 	  of unique features.
 
 	  http://www.maier-komor.de/mbuffer.html
 
-comment "mbuffer needs a toolchain w/ dynamic library"
-	depends on BR2_STATIC_LIBS
+comment "mbuffer needs a toolchain w/ dynamic library, threads"
+	depends on BR2_STATIC_LIBS || !BR2_TOOLCHAIN_HAS_THREADS