can-utils: add dependency on NPTL

canfdtest.c assumes that clock_nanosleep() is always available. But it
is only available with NPTL. Since it unconditionally uses it, we add
dependency on NPTL.

Fixes:
http://autobuild.buildroot.net/results/fd97aa57747a546c799caf094aafe0d1d1225863
http://autobuild.buildroot.net/results/1313f91df134035159e677c6b4a63838c75d074c
http://autobuild.buildroot.net/results/a1ac495c5e38e5d0777c431fc6a2e4b5bff7c2ad
http://autobuild.buildroot.net/results/978bee40049896bd6e093fa31c5eb7673e05a6b8
http://autobuild.buildroot.net/results/c692e96de1b4fdadf720ead8249a44c21fe945f1

Signed-off-by: Yegor Yefremov <yegorslists@googlemail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/can-utils/Config.in

@@ -1,9 +1,14 @@
 config BR2_PACKAGE_CAN_UTILS
 	bool "can-utils"
 	depends on BR2_USE_MMU # fork()
+	depends on BR2_TOOLCHAIN_HAS_THREADS_NPTL # clock_nanosleep()
 	help
 	  SocketCAN is a set of open source CAN drivers and a
 	  networking stack.
 	  This package provides various tools for this stack.
 
 	  http://elinux.org/Can-utils
+
+comment "can-utils needs a toolchain w/ NPTL"
+	depends on !BR2_TOOLCHAIN_HAS_THREADS_NPTL
+	depends on BR2_USE_MMU