test: disable ptytest unless HAS_PTY

Signed-off-by: Bernhard Reutner-Fischer <rep.dot.nop@gmail.com>

test/stdlib/Makefile.in

@@ -5,3 +5,9 @@ DODIFF_qsort       := 1
 DODIFF_testatexit  := 1
 DODIFF_teston_exit := 1
 DODIFF_teststrtol  := 1
+
+TESTS_DISABLED :=
+ifeq ($(UCLIBC_HAS_PTY),)
+TESTS_DISABLED += ptytest
+endif
+