tests/disk/disk_copy.c: use setenv instead of putenv, this is more valgrind friendly

tests/disk/disk_copy.c

@@ -32,12 +32,20 @@
 #define	NX	(30*1000000/sizeof(double))
 #endif
 
+#if !defined(STARPU_HAVE_SETENV)
+#warning setenv is not defined. Skipping test
+int main(int argc, char **argv)
+{
+	return STARPU_TEST_SKIPPED;
+}
+#else
+
 int main(int argc, char **argv)
 {
 	double * A,*B,*C,*D,*E,*F;
 
 	/* limit main ram to force to push in disk */
-	putenv("STARPU_LIMIT_CPU_MEM=160");
+	setenv("STARPU_LIMIT_CPU_MEM", "160", 1);
 
 	/* Initialize StarPU with default configuration */
 	int ret = starpu_init(NULL);
@@ -120,3 +128,4 @@ enodev:
 enoent:
 	return STARPU_TEST_SKIPPED;
 }
+#endif