Use <support/test-driver.c> in stdlib/tst-strtod-overflow.c

This downstream-only patch is needed because test-skeleton.c contains

a copy of the old test skeleton (unlike upstream), resulting in the

following error:

In file included from tst-strtod-overflow.c:53:0:

../test-skeleton.c:65:20: error: static declaration of 'test_dir' follows non-static declaration

 static const char *test_dir;

                    ^

In file included from tst-strtod-overflow.c:23:0:

../support/test-driver.h:65:20: note: previous declaration of 'test_dir' was here

 extern const char *test_dir;

                    ^

diff --git a/stdlib/tst-strtod-overflow.c b/stdlib/tst-strtod-overflow.c

index fd1be79f3f58c64b..2b30947d9a9fa03a 100644

--- a/stdlib/tst-strtod-overflow.c

+++ b/stdlib/tst-strtod-overflow.c

@@ -48,6 +48,4 @@ do_test (void)

   return 0;

 }

-#define TEST_FUNCTION do_test ()

-#define TIMEOUT 5

-#include "../test-skeleton.c"

+#include <support/test-driver.c>