build: explicitly require libndn-cxx >= 0.8.0

Change-Id: I029ded8120e149e945a74feaf58739960dbfa3f2

wscript

@@ -25,8 +25,9 @@ def configure(conf):
 
     conf.env.WITH_TESTS = conf.options.with_tests
 
-    conf.check_cfg(package='libndn-cxx', args=['--cflags', '--libs'], uselib_store='NDN_CXX',
-                   pkg_config_path=os.environ.get('PKG_CONFIG_PATH', '%s/pkgconfig' % conf.env.LIBDIR))
+    pkg_config_path = os.environ.get('PKG_CONFIG_PATH', f'{conf.env.LIBDIR}/pkgconfig')
+    conf.check_cfg(package='libndn-cxx', args=['libndn-cxx >= 0.8.0', '--cflags', '--libs'],
+                   uselib_store='NDN_CXX', pkg_config_path=pkg_config_path)
 
     boost_libs = ['system', 'iostreams']
     if conf.env.WITH_TESTS: