package/libtracefs: needs threads

libtracefs needs threads resulting in the following build failure since
its addition in commit b1dbd3f679e6660325472e3fdca72127d74e6929:

In file included from /home/autobuild/autobuild/instance-2/output-1/host/xtensa-buildroot-linux-uclibc/sysroot/usr/include/stdio.h:27,
                 from ../src/tracefs-instance.c:10:
/home/autobuild/autobuild/instance-2/output-1/host/xtensa-buildroot-linux-uclibc/sysroot/usr/include/features.h:218:5: warning: #warning requested reentrant code, but thread support was disabled [-Wcpp]
  218 | #   warning requested reentrant code, but thread support was disabled
      |     ^~~~~~~
../src/tracefs-instance.c:20:10: fatal error: pthread.h: No such file or directory
   20 | #include <pthread.h>
      |          ^~~~~~~~~~~

Fixes:
 - http://autobuild.buildroot.org/results/e0a8dd0781a1d1824a4cb78f47dcff4055083959

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Reviewed-by: Giulio Benetti <giulio.benetti@benettiengineering.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

package/libtracefs/Config.in

@@ -1,5 +1,6 @@
 config BR2_PACKAGE_LIBTRACEFS
 	bool "libtracefs"
+	depends on BR2_TOOLCHAIN_HAS_THREADS
 	depends on !BR2_STATIC_LIBS # libtraceevent
 	select BR2_PACKAGE_LIBTRACEEVENT
 	help
@@ -8,5 +9,5 @@ config BR2_PACKAGE_LIBTRACEFS
 
 	  https://git.kernel.org/pub/scm/libs/libtrace/libtraceevent.git/
 
-comment "libtracefs needs a toolchain w/ dynamic library"
-	depends on BR2_STATIC_LIBS
+comment "libtracefs needs a toolchain w/ threads, dynamic library"
+	depends on !BR2_TOOLCHAIN_HAS_THREADS || BR2_STATIC_LIBS

package/linux-tools/Config.in

@@ -104,6 +104,7 @@ endif
 
 config BR2_PACKAGE_LINUX_TOOLS_RTLA
 	bool "rtla"
+	depends on BR2_TOOLCHAIN_HAS_THREADS # libtracefs
 	depends on !BR2_STATIC_LIBS # libtracefs
 	select BR2_PACKAGE_LINUX_TOOLS
 	select BR2_PACKAGE_LIBTRACEFS
@@ -124,8 +125,8 @@ config BR2_PACKAGE_LINUX_TOOLS_RTLA
 	  not available in Buildroot, so only rtla in kernels 5.19
 	  onwards is actually supported in Buildroot.
 
-comment "rtla needs a toolchain w/ dynamic library"
-	depends on BR2_STATIC_LIBS
+comment "rtla needs a toolchain w/ threads, dynamic library"
+	depends on !BR2_TOOLCHAIN_HAS_THREADS || BR2_STATIC_LIBS
 
 config BR2_PACKAGE_LINUX_TOOLS_SELFTESTS
 	bool"selftests"

package/trace-cmd/Config.in

@@ -4,6 +4,7 @@ config BR2_PACKAGE_TRACE_CMD
 	depends on BR2_TOOLCHAIN_HAS_THREADS_NPTL
 	depends on BR2_USE_MMU # fork()
 	depends on !BR2_STATIC_LIBS # dlopen()
+	depends on BR2_TOOLCHAIN_HAS_THREADS # libtracefs
 	select BR2_PACKAGE_LIBTRACEEVENT
 	select BR2_PACKAGE_LIBTRACEFS
 	help
@@ -16,6 +17,7 @@ config BR2_PACKAGE_TRACE_CMD
 
 	  http://git.kernel.org/cgit/linux/kernel/git/rostedt/trace-cmd.git
 
-comment "trace-cmd needs a toolchain w/ NPTL, dynamic library"
+comment "trace-cmd needs a toolchain w/ threads, NPTL, dynamic library"
 	depends on BR2_USE_MMU
-	depends on !BR2_TOOLCHAIN_HAS_THREADS_NPTL || BR2_STATIC_LIBS
+	depends on !BR2_TOOLCHAIN_HAS_THREADS || \
+		!BR2_TOOLCHAIN_HAS_THREADS_NPTL || BR2_STATIC_LIBS