build: load sanitizers last in wscript to prevent boost link failure

refs #3828

Change-Id: I52c93e8c75c4690314fdb4767a5427cf9f9c225a

wscript

@@ -18,7 +18,7 @@ def options(opt):
 
 def configure(conf):
     conf.load(['compiler_cxx', 'gnu_dirs',
-               'default-compiler-flags', 'sanitizers', 'sphinx_build', 'boost'])
+               'default-compiler-flags', 'sphinx_build', 'boost'])
 
     if 'PKG_CONFIG_PATH' not in os.environ:
         os.environ['PKG_CONFIG_PATH'] = Utils.subst_vars('${LIBDIR}/pkgconfig', conf.env)
@@ -34,6 +34,8 @@ def configure(conf):
 
     conf.recurse('tools')
 
+    conf.load('sanitizers')
+
 def build(bld):
     bld.env['VERSION'] = VERSION