Bug #1251

- #1251 tests should sanitize TASKDATA and TASKRC env vars (thanks to Jakub
  Wilk).

test/rx.t.cpp

@@ -26,6 +26,7 @@
 ////////////////////////////////////////////////////////////////////////////////
 
 #include <cmake.h>
+#include <stdlib.h>
 #include <Context.h>
 #include <RX.h>
 #include <test.h>
@@ -36,6 +37,10 @@ int main (int argc, char** argv)
 {
   UnitTest ut (23);
 
+  // Ensure environment has no influence.
+  unsetenv ("TASKDATA");
+  unsetenv ("TASKRC");
+
   std::string text = "This is a test.";
 
   RX r1 ("i. ", true);