package/linux-tools: thermal needs threads

tmon needs threads since its addition in kernel 3.13 and
https://github.com/torvalds/linux/commit/94f69966faf8e70bd655ea25f9dd5b9400567b75:

tmon.c:23:10: fatal error: pthread.h: No such file or directory
   23 | #include <pthread.h>
      |          ^~~~~~~~~~~

Fixes:
 - http://autobuild.buildroot.org/results/d7b3d15ebf80ca6dbbbd4554af541182c777e4de

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

package/linux-tools/Config.in

@@ -117,12 +117,16 @@ comment "selftests needs BR2_PACKAGE_BUSYBOX_SHOW_OTHERS and a toolchain w/ dyna
 
 config BR2_PACKAGE_LINUX_TOOLS_TMON
 	bool "tmon"
+	depends on BR2_TOOLCHAIN_HAS_THREADS
 	select BR2_PACKAGE_LINUX_TOOLS
 	select BR2_PACKAGE_NCURSES
 	help
 	  tmon is a terminal-based tool (using curses) that allows the
 	  user to access thermal information about the system.
 
+comment "tmon needs a toolchain w/ threads"
+	depends on !BR2_TOOLCHAIN_HAS_THREADS
+
 config BR2_PACKAGE_LINUX_TOOLS_HV
 	bool "hv"
 	depends on BR2_i386 || BR2_x86_64