* strings.h (strechr): New function.

* uinfo.cc (pwdgrp::next_str): Search only for input char in string.  Return
EOS on failure.  Don't check for NULL since it shouldn't be possible.
(pwdgrp::add_line): Revert to replacing '\n' in input line with '\0'.
(pwdgrp::next_num): Pass explicit separator character to next_str.
* grp.cc (pwdgrp::parse_group): Ditto.
* passwd.cc (pwdgrp::parse_passwd): Ditto.  Revamp test for garbage input.
* pwdgrp.h (pwdgrp::next_str): Don't use default parameter.

winsup/cygwin/pwdgrp.h

@@ -46,7 +46,7 @@ class pwdgrp
   void read_group ();
   char *add_line (char *);
   char *raw_ptr () const {return lptr;}
-  char *next_str (char = 0);
+  char *next_str (char);
   bool next_num (unsigned long&);
   bool next_num (unsigned int& i)
   {