configtree: T9261: bind libvyosconfig once instead of per ConfigTree

Every ConfigTree re-opened libvyosconfig with cdll.LoadLibrary and re-declared
all 31 function prototypes inline in __init__. DiffTree and the twelve
module-level helpers repeated the pattern per call, and since a DiffTree builds
six further trees internally, a single one performed seven dlopens and roughly
200 argtypes/restype assignments. referencetree.py had its own copy.

Declare the prototypes once in a _PROTOTYPES table and hand out an lru_cache'd
wrapper keyed on libpath. Symbols are resolved on first use rather than up
front, because not every build of the library exports every entry point and the
previous code only failed on symbols actually called. referencetree.py shares
the cache and picks up LIBPATH from configtree, so it now honours the
/tmp/libvyosconfig/_build development path instead of hardcoding the install
path.

  ConfigTree()   72.3 -> 6.3 us   (-91%, 11.5x)
  DiffTree()    397.3 -> 34.7 us  (-91%, 11.4x)

Two prototypes were wrong and are fixed by declaring them in one place.
validate_tree_filter had no restype, so ctypes defaulted to c_int and truncated
the returned tree pointer to 32 bits before ConfigTree(address=...) saw it;
harmless while the heap stays below 4 GB, corrupt above it. get_subtree
declared two argtypes but is called with three, leaving with_node unchecked.

0 files changed, 0 insertions, 0 deletions