build: reflect gnulib changes to tempname

build: reflect gnulib changes to tempname

In glibc 2.11 and gnulib, gen_tempname added a parameter
suffixlen (unfortunately, it is typed as int rather than
size_t, for historical compatibility to a poor choice by BSD).

* gnulib: Import latest changes.
* gl/lib/tempname.h.diff: Accommodate new suffixlen parameter.
* gl/lib/tempname.c.diff (check_x_suffix): Allow for X in suffix
beyond x_suffix_len.
(gen_tempname_len): Add suffixlen parameter.
(__gen_tempname): Update caller.
* src/mktemp.c (mkstemp_len, mkdtemp_len): Update callers.