package/valgrind: needs threads

valgrind needs threads since the addition of vgdb in
https://sourceware.org/git/?p=valgrind.git;a=commit;h=2ee9e9048658773ceef3d30eb79f44764a024f3c:

vgdb.c:37:10: fatal error: pthread.h: No such file or directory
   37 | #include <pthread.h>
      |          ^~~~~~~~~~~

Fixes:
 - http://autobuild.buildroot.org/results/ffa2dbfd6d5efcc50d447c0e759fb4ffce0b59b9

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/valgrind/Config.in

@@ -7,14 +7,15 @@ config BR2_PACKAGE_VALGRIND_ARCH_SUPPORTS
 	default y if BR2_powerpc || BR2_powerpc64 || BR2_powerpc64le
 	depends on !BR2_MIPS_SOFT_FLOAT
 
-comment "valgrind needs a toolchain w/ dynamic library"
+comment "valgrind needs a toolchain w/ dynamic library, threads"
 	depends on BR2_PACKAGE_VALGRIND_ARCH_SUPPORTS
-	depends on BR2_STATIC_LIBS
+	depends on BR2_STATIC_LIBS || !BR2_TOOLCHAIN_HAS_THREADS
 
 config BR2_PACKAGE_VALGRIND
 	bool "valgrind"
 	depends on BR2_PACKAGE_VALGRIND_ARCH_SUPPORTS
 	depends on !BR2_STATIC_LIBS
+	depends on BR2_TOOLCHAIN_HAS_THREADS
 	help
 	  Tool for debugging and profiling Linux programs.