Adjust a few function for future compat

Author: mgreter

src/fn_miscs.cpp

@@ -32,7 +32,7 @@ namespace Sass {
       }
     }
 
-    Signature global_variable_exists_sig = "global-variable-exists($name)";
+    Signature global_variable_exists_sig = "global-variable-exists($name, $module: null)";
     BUILT_IN(global_variable_exists)
     {
       std::string s = unquote(ARGSTRC("$name")->value());
@@ -45,7 +45,7 @@ namespace Sass {
       }
     }
 
-    Signature function_exists_sig = "function-exists($name)";
+    Signature function_exists_sig = "function-exists($name, $module: null)";
     BUILT_IN(function_exists)
     {
       String_Constant* ss = Cast<String_Constant>(env["$name"]);
@@ -63,7 +63,7 @@ namespace Sass {
       }
     }
 
-    Signature mixin_exists_sig = "mixin-exists($name)";
+    Signature mixin_exists_sig = "mixin-exists($name, $module: null)";
     BUILT_IN(mixin_exists)
     {
       std::string s = unquote(ARGSTRC("$name")->value());
@@ -208,7 +208,7 @@ namespace Sass {
       return SASS_MEMORY_NEW(Boolean, pstate, d_env.has_lexical("@content[m]"));
     }
 
-    Signature get_function_sig = "get-function($name, $css: false)";
+    Signature get_function_sig = "get-function($name, $css: false, $module: null)";
     BUILT_IN(get_function)
     {
       String_Constant* ss = Cast<String_Constant>(env["$name"]);