package/uftrace: needs threads

uftrace needs threads since its addition to buildroot in commit
09c97972d9f90b69cfc36f9ffe9e22c13daf9307

Fixes:
 - http://autobuild.buildroot.org/results/d27c34a2f773aeb3c806d56dd2468d17caf2fbc6

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

package/uftrace/Config.in

@@ -8,6 +8,7 @@ config BR2_PACKAGE_UFTRACE_ARCH_SUPPORTS
 config BR2_PACKAGE_UFTRACE
 	bool "uftrace"
 	depends on BR2_PACKAGE_UFTRACE_ARCH_SUPPORTS
+	depends on BR2_TOOLCHAIN_HAS_THREADS
 	select BR2_PACKAGE_ARGP_STANDALONE if \
 	       BR2_TOOLCHAIN_USES_UCLIBC || \
 	       BR2_TOOLCHAIN_USES_MUSL
@@ -20,3 +21,6 @@ config BR2_PACKAGE_UFTRACE
 	  analysis of the program execution and performance.
 
 	  https://github.com/namhyung/uftrace
+
+comment "uftrace needs a toolchain w/ threads"
+	depends on !BR2_TOOLCHAIN_HAS_THREADS