This patch tightens up our determination of whether we can use

This patch tightens up our determination of whether we can use
getpw{nam,uid}_r, and using the set flags, creates macros providing a
consistent API, and if possible thread safety.

* configure.in: Don't check for getpwnam_r and getpwuid_r with AC_CHECK_FUNCS;
use AC_CHECK_FUNC, and only set shell variables.  Run stricter tests on return
types and numbers of arguments, and only define the C macros if these
parameters can actually be determined.
* k5-platform.h (k5_getpwnam_r, k5_getpwuid_r): New macros.

ticket: 2982
status: open

git-svn-id: svn://anonsvn.mit.edu/krb5/trunk@17155 dc483132-0cff-0310-8789-dd5450dbe970