Re-pin stable for C stdio/socket PAL bridge

• Type: chore
• Status: done
• Closed 2026-06-29 (board cleanup): C stdio PAL bridge landed (4c81feae) and was blessed before pin v82; tree now at v85. Re-pin no longer pending.
• Track: A/C handoff, affects Track B lib/crtl gates
• Opened: 2026-06-27
• Found-by: Track B crtl work, after implementing bug-c-crtl-fopen-missing

Problem

The pinned Track B compiler (stable_linux_amd64/default/pinned, currently stable v81) self-hosts cleanly, but it cannot run the new crtl PAL-bridge regressions as pinned gates yet.

File stdio:

stable_linux_amd64/default/pinned \
  -Ilib/crtl/include -Ilib/crtl/src \
  test/cfile_stdio_b87.c /tmp/cfile_stdio_b87_pinned
/tmp/cfile_stdio_b87_pinned

The compile succeeds, but the executable fails at load time:

symbol lookup error: /tmp/cfile_stdio_b87_pinned: undefined symbol: __pxx_write

Sockets show the same pin lag:

stable_linux_amd64/default/pinned \
  -Ilib/crtl/include -Ilib/crtl/src \
  test/csocket_loopback_b88.c /tmp/csocket_loopback_b88_pinned
/tmp/csocket_loopback_b88_pinned

The compile succeeds, but the executable fails at load time:

symbol lookup error: /tmp/csocket_loopback_b88_pinned: undefined symbol: __pxx_socket

This is not a crtl body failure. A compiler generated from the current source by the pinned compiler resolves the Pascal-backed pxxcio bridge correctly:

stable_linux_amd64/default/pinned compiler/compiler.pas /tmp/pxx-sc-g1
/tmp/pxx-sc-g1 -Ilib/crtl/include -Ilib/crtl/src \
  test/cfile_stdio_b87.c /tmp/cfile_stdio_b87_g1
/tmp/cfile_stdio_b87_g1   # returns 42

make selfcheck is also green with pinned:

self-host fixedpoint OK (g2 == g3)
=== selfcheck OK ===

Acceptance

• Re-pin stable so stable_linux_amd64/default/pinned includes the C driver behavior that auto-pulls/binds lib/rtl/pxxcio.pas for C programs.
• The pinned compiler can compile and run test/cfile_stdio_b87.c, returning 42.
• The pinned compiler can compile and run test/csocket_loopback_b88.c, returning 42.
• If the regression is kept in make test-core, the checked-in compiler/pascal26 seed and/or pinned Track B flow should be consistent with that gate.

Log

• 2026-06-27 — Filed from Track B crtl fopen work. Current generated compiler passes the regression; pinned v81 compiles it but produces a runtime unresolved __pxx_write.
• 2026-06-27 — Extended from Track B crtl socket work. Current generated compiler passes test/csocket_loopback_b88.c; pinned v81 compiles it but produces a runtime unresolved __pxx_socket.
• 2026-06-27 audit — Still open. Current compiler/pascal26 passes both test/cfile_stdio_b87.c and test/csocket_loopback_b88.c; pinned stable still fails at runtime with unresolved __pxx_write / __pxx_socket.