Fix thekla_atlas build

clang doesn't like c++ versions being supplied to build c source files.

modules/thekla_unwrap/SCsub

@@ -55,7 +55,7 @@ if env['builtin_thekla_atlas']:
     env_thekla_unwrap.Append(CPPPATH=[thirdparty_dir, thirdparty_dir + "/poshlib", thirdparty_dir + "/nvcore", thirdparty_dir + "/nvmesh"])
 
     # upstream uses c++11
-    env_thekla_unwrap.Append(CCFLAGS="-std=gnu++11")
+    env_thekla_unwrap.Append(CXXFLAGS="-std=gnu++11")
 
     if env["platform"] == 'x11':
         env_thekla_unwrap.Append(CCFLAGS=["-DNV_OS_LINUX"])

modules/thekla_unwrap/config.py

@@ -3,5 +3,5 @@ def can_build(platform):
 
 def configure(env):
     if not env['tools']:
-        env['module_thekla_unwrap_enabled'] = False
+        env['builtin_thekla_atlas'] = False
         env.disabled_modules.append("thekla_unwrap")