[PATCH] misc: Add twalk_r function

[Joseph Myers]

I'm seeing (at least with GCC 8):

tst-tsearch.c: In function 'walk_tree.constprop':
tst-tsearch.c:231:3: error: 'first_list_size' may be used uninitialized in this function [-Werror=maybe-uninitialized]
   for (size_t i = 0; i < first_list_size && i < walk_trace_size (&walk_trace);
   ^~~

https://sourceware.org/ml/libc-testresults/2019-q2/msg00121.html

-- 
Joseph S. Myers
joseph@codesourcery.com