Use TESTING_IN_BUILD_TREE in params.exp

	* gcc.dg/params/params.exp: Replace file exists with
	TESTING_IN_BUILD_TREE.

From-SVN: r239119

gcc/testsuite/ChangeLog

+2016-08-04  Martin Liska  <mliska@suse.cz>
+
+	* gcc.dg/params/params.exp: Replace file exists with
+	TESTING_IN_BUILD_TREE.
+
 2016-08-04  Marek Polacek  <polacek@redhat.com>
 
 	PR c++/70229

gcc/testsuite/gcc.dg/params/params.exp

@@ -32,7 +32,7 @@ proc param_run_test { param_name param_value } {
 }
 
 set options_file "$objdir/../../params.options"
-if { [file exists $options_file] == 0 } {
+if { [info exists TESTING_IN_BUILD_TREE] == 0 } {
   return
 }