cursor for iterating over ccaches

cursor for iterating over ccaches

Some ccache back ends need per-type cursors implemented.

	* src/include/k5-int.h: Declare krb5_cc_ptcursor.  Update
	krb5_cc_ops vector to include functions for ptcursor and some
	not-yet-implemented functionality.

	* src/include/krb5/krb5.hin: Prototype krb5_cccol_cursor_new,
	krb5_cccol_cursor_next, krb5_cccol_cursor_free.

	* src/lib/krb5/ccache/Makefile.in: Compile cccursor.c.  Build
	t_cccursor.

	* src/lib/krb5/ccache/cccursor.c: Implementation of cursor for
	iterating over ccaches.

	* src/lib/krb5/ccache/ccbase.c: Add typecursor functionality for
	iteration over registered ccache types.

	* src/lib/krb5/ccache/cc_memory.c: Implmement per-type ccache
	cursor functionality.

	* src/lib/krb5/ccache/cc_mslsa.c:
	* src/lib/krb5/ccache/cc_file.c:
	* src/lib/krb5/ccache/ccapi/stdcc.c: Add place-holder ops vector
	entries.

	* src/lib/krb5/ccache/t_cccursor.c: New test of ccache cursor
	functionality.

	* src/lib/krb5/os/ccdefname.c (krb5int_cc_os_default_name): New
	function to return the OS-specific default ccache name.

ticket: new
status: open

git-svn-id: svn://anonsvn.mit.edu/krb5/trunk@18651 dc483132-0cff-0310-8789-dd5450dbe970