ycurses: get it building on modern GCC, verify in Docker (task 9s0)

ycurses shares no source files with ychat/yhttpd (it's an ncurses UI
toolkit, not part of the httpd/socket engine), so none of the sock/reqp/
html/logd/tool fixes apply here - only the same class of toolchain-gate
bugs did:

- Top-level configure's g++ 3.x version gate now accepts any GNU g++
  (same fix as yhttpd/configure).
- scripts/config.pl silently BEGIN-failed on modern Perl (`use
  scripts::modules::file` needs "." on @INC, dropped by Perl 5.26+); the
  "yes" default answer was never actually read. Fixed with `perl -I.`
  (also applied to yhttpd/configure, which had the same latent bug).
- src/configure's library search paths predate 64-bit multilib distros
  (no /usr/lib64), so installed libpanel/libmenu/libncurses were reported
  "NOT OK" on Rocky Linux 9 (also backported to yhttpd/src/configure).
- attributes.h declared `set<int> set_attr` (std::set, via `using
  namespace std`) and separately two member functions literally named
  `set` - GCC 11 treats that as ill-formed ("changes meaning of 'set'"),
  not just a warning. Renamed both overloads to set_attr_flag; no
  external caller used the bare set(...)/set(int) names.

Verified in a Rocky Linux 9 container: builds clean, links, and runs -
initializes curses, draws the demo screen using color/attributes
(exercising the fix above), exits cleanly. Added Dockerfile (build
verification only - it's an interactive demo, not a service) and
BUILD.md documenting the fixes and one pre-existing, deliberately
unfixed bug (unset() never actually clears an attribute).

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

1 files changed, 30 insertions, 0 deletions

diff --git a/ycurses/Dockerfile b/ycurses/Dockerfile
new file mode 100644
index 0000000..c27b45c
--- /dev/null
+++ b/ycurses/Dockerfile
@@ -0,0 +1,30 @@
+# ycurses — Docker build verification
+#
+# ycurses is a standalone ncurses C++ toolkit (windows/menus/attributes/
+# color), demoed by an interactive full-screen menu (src/main.cpp) - there
+# is no server/service to run, so unlike ../yhttpd this image is a build
+# check, not a deployable runtime.
+#
+# Builds entirely in a container on Rocky Linux 9, whose GCC 11 accepts the
+# legacy C++ this ~2005 codebase uses once the fixes below are applied.
+
+FROM rockylinux:9 AS builder
+
+RUN dnf -y install \
+        gcc-c++ \
+        make \
+        perl \
+        which \
+        ncurses-devel \
+    && dnf clean all
+
+WORKDIR /build/ycurses
+COPY . .
+RUN rm -rf obj bin backuped g++.version make.version src/Makefile src/includes.add src/libs.add
+
+# config.pl is interactive (asks yes/no); "yes" = use default before-compile
+# options.
+RUN echo yes | ./configure \
+    && make
+
+ENTRYPOINT ["/build/ycurses/bin"]