build: pin -std=c11 for instrument-hooks core.c

The Zig-generated dist/core.c is rejected under C23 (GCC 15's default),
so pin C11 in the native extension build.

Author: not-matthias

setup.py

@@ -41,6 +41,7 @@
     # upstream silences; in particular distros like Nix/Debian/Fedora inject
     # -Werror=format-security, which would otherwise fail the build.
     extra_compile_args=[
+        "-std=c11",
         "-Wno-format",
         "-Wno-format-security",
         "-Wno-unused-but-set-variable",