build: Move test support to librtemstest.a

One reason to move the test support into a dedicated library are the
standard output __wrap_*() functions.  They may conflict with
application level wrappers.

Update #3199.

cpukit/libtest/testwrappers.c

@@ -0,0 +1,48 @@
+/*
+ * Copyright (c) 2017 Chris Johns <chrisj@rtems.org>. All rights reserved.
+ *
+ * The license and distribution terms for this file may be
+ * found in the file LICENSE in this distribution or at
+ * http://www.rtems.org/license/LICENSE.
+ */
+
+#ifdef HAVE_CONFIG_H
+  #include "config.h"
+#endif
+
+#include <rtems/test.h>
+
+int __wrap_printf(const char* format, ...);
+int __wrap_puts(const char *str);
+int __wrap_putchar(int c);
+
+int __wrap_printf(
+ const char* format,
+  ...
+)
+{
+  va_list ap;
+  int len;
+  va_start(ap, format);
+  len = rtems_vprintf(
+    &rtems_test_printer,
+    format,
+    ap
+  );
+  va_end(ap);
+  return len;
+}
+
+int __wrap_puts(
+  const char *str
+)
+{
+  return rtems_test_printf( "%s\n", str );
+}
+
+int __wrap_putchar(
+  int c
+)
+{
+  return rtems_test_printf( "%c", c );
+}