context: add leafref_linking options

This patch adds leafref_linking context option, which allows the usage
of lyd_leafref_get_links and lyd_leafref_link_node_tree functions, whose
support will be added in the next commit.

Closes: #108
Signed-off-by: Stefan Gula <steweg@gmail.com>
Signed-off-by: Samuel Gauthier <samuel.gauthier@6wind.com>

cffi/cdefs.h

@@ -15,6 +15,7 @@ struct ly_ctx;
 #define LY_CTX_REF_IMPLEMENTED ...
 #define LY_CTX_SET_PRIV_PARSED ...
 #define LY_CTX_LEAFREF_EXTENDED ...
+#define LY_CTX_LEAFREF_LINKING ...
 
 
 typedef enum {

libyang/context.py

@@ -30,6 +30,7 @@ def __init__(
         disable_searchdir_cwd: bool = True,
         explicit_compile: Optional[bool] = False,
         leafref_extended: bool = False,
+        leafref_linking: bool = False,
         yanglib_path: Optional[str] = None,
         yanglib_fmt: str = "json",
         cdata=None,  # C type: "struct ly_ctx *"
@@ -47,6 +48,8 @@ def __init__(
             options |= lib.LY_CTX_EXPLICIT_COMPILE
         if leafref_extended:
             options |= lib.LY_CTX_LEAFREF_EXTENDED
+        if leafref_linking:
+            options |= lib.LY_CTX_LEAFREF_LINKING
         # force priv parsed
         options |= lib.LY_CTX_SET_PRIV_PARSED