log4cpp: needs threads

Fixes:
http://autobuild.buildroot.net/results/cf9/cf942e4b8a5259414a4dcea6fa4b75183435394a/

Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/log4cpp/Config.in

@@ -1,6 +1,7 @@
 config BR2_PACKAGE_LOG4CPP
 	bool "log4cpp"
 	depends on BR2_INSTALL_LIBSTDCPP
+	depends on BR2_TOOLCHAIN_HAS_THREADS
 	help
 	  Log4cpp is library of C++ classes for flexible logging to
 	  files, syslog, IDSA and other destinations.  It is modeled
@@ -9,5 +10,5 @@ config BR2_PACKAGE_LOG4CPP
 
 	  http://log4cpp.sourceforge.net/
 
-comment "log4cpp needs a toolchain w/ C++"
-	depends on !BR2_INSTALL_LIBSTDCPP
+comment "log4cpp needs a toolchain w/ C++, threads"
+	depends on !BR2_INSTALL_LIBSTDCPP || !BR2_TOOLCHAIN_HAS_THREADS