Core: Accept c_bool as a ctypes type

c_bool was missing from the ctypes table, so c_bool(5) was an unknown
call, its slot was never allocated, and the error read "Undefined
variable". It is C's _Bool: one bit, like the True/False locals, never
negative, and a value narrows to it by comparing with zero, which the
signedness rules already apply to 1-bit types. It works as a local, a
struct field, a map value and a global; in BTF it is a one-byte _Bool.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

Author: r41k0u

pythonbpf/type_deducer.py

@@ -113,6 +113,9 @@ def signedness(ty) -> bool:
     "c_longlong": 64,
     # A pointer-sized integer; treated as unsigned like uintptr_t.
     "c_void_p": 64,
+    # C's _Bool: one bit to LLVM (as True/False locals already are). It is
+    # never negative, and a value narrows to it by comparing with zero.
+    "c_bool": 1,
 }