package/ntpsec: fix dependencies

Add python3 dependencies to avoid the following build failure raised
since the addition of the package in commit
27b8d0ba8c4004819e092fb81c0f64f284b3aa4a:

Makefile:576: *** libffi is in the dependency chain of python3 that has added it to its _DEPENDENCIES variable without selecting it or depending on it from Config.in.  Stop.

Fixes:
 - http://autobuild.buildroot.org/results/2893c213f49d37a0878dcf14ec68ef991471c70f

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

package/ntpsec/Config.in

@@ -1,5 +1,9 @@
 config BR2_PACKAGE_NTPSEC
 	bool "ntpsec"
+	depends on BR2_USE_MMU # python3
+	depends on BR2_USE_WCHAR # python3
+	depends on BR2_TOOLCHAIN_HAS_THREADS # python3
+	depends on !BR2_STATIC_LIBS # python3
 	select BR2_PACKAGE_LIBCAP
 	select BR2_PACKAGE_OPENSSL
 	select BR2_PACKAGE_PYTHON3
@@ -26,3 +30,8 @@ config BR2_PACKAGE_NTPSEC_NTS
 	  Enable Network Time Security (NTS) support.
 
 endif
+
+comment "ntpsec needs a toolchain w/ wchar, threads, dynamic library"
+	depends on BR2_USE_MMU
+	depends on !BR2_USE_WCHAR || !BR2_TOOLCHAIN_HAS_THREADS || \
+		BR2_STATIC_LIBS