[roottest] simplify treeformula/formulaio test

Author: linev

roottest/root/treeformula/formulaio/.rootrc

@@ -1,6 +1,4 @@
 ROOTTEST_ADD_TEST(old-formula
-  PRECMD ${CMAKE_COMMAND} -E copy
-    ${CMAKE_CURRENT_SOURCE_DIR}/hsimple.31000.root
-    ${CMAKE_CURRENT_BINARY_DIR}/hsimple.31000.root
-  MACRO runoldFormulaTest.C
-  OUTREF oldFormulaTest.ref)
+                  COPY_TO_BUILDDIR hsimple.31000.root
+                  MACRO runoldFormulaTest.C
+                  OUTREF oldFormulaTest.ref)