libsepol/cil: Add function to search the CIL AST for an AV rule.

The search will be considered a success if any rule is found that
at least partially matches all parts (src type, tgt type, and class-
perms) of the target rule.

For example, for a target of (allow domain file_type (file (read write)
the rule (allow init_t init_exec_t (file (read exec)) will match.

Signed-off-by: James Carter <jwcart2@tycho.nsa.gov>
3 files changed