mes: Add setenv.

* src/posix.c (setenv_): New function.
* tests/base.test ("setenv, getenv"): Test it.

src/posix.c

@@ -135,6 +135,15 @@ getenv_ (SCM s) ///((name . "getenv"))
   return p ? MAKE_STRING (cstring_to_list (p)) : cell_f;
 }
 
+SCM
+setenv_ (SCM s, SCM v) ///((name . "setenv"))
+{
+  char buf[1024];
+  strcpy (buf, string_to_cstring (s));
+  setenv (buf, string_to_cstring (v), 1);
+  return cell_unspecified;
+}
+
 SCM
 access_p (SCM file_name, SCM mode)
 {

tests/base.test

@@ -116,4 +116,11 @@ exit $?
     (pass-if-not "#<eof>"
                  (char? (integer->char -1))))
 
+(pass-if-equal "setenv, getenv"
+    "bar"
+  (begin
+    (setenv "foo" "bar")
+    (getenv "bar")
+    (getenv "foo")))
+
 (result 'report)