scons: Need c99 also when cross compiling.
diff --git a/SConstruct b/SConstruct
index 19d8b13..96dc09a 100644
--- a/SConstruct
+++ b/SConstruct
@@ -150,6 +150,9 @@
     host_env['hostonly'] = True
     assert host_env['crosscompile'] == False
 
+    if host_env['msvc']:
+        host_env.Append(CPPPATH = ['#include/c99'])
+
     Export(env = host_env)
 
     SConscript(