merge: bring in gnu.org/gcc/v8 recipe (companion PR pkgxdev#13070)

mysql.com/v5_7 build-depends on gnu.org/gcc/v8 (linux only) for the
InnoDB pre-C++17 idioms. The v8 recipe lives on a separate open PR;
merging it here so CI can resolve the dep and bottle this PR.

If pkgxdev#13070 lands first, this merge is a no-op.

Author: tannevaled

projects/gnu.org/gcc/v8/package.yml

@@ -0,0 +1,99 @@
+# GCC 8 — legacy version for old-vendored-C++ projects.
+#
+# Many projects vendoring older C++ libraries (RocksDB 6.3.x, old
+# MySQL 5.7, old InnoDB, pre-C++17 codebases generally) hit the
+# stricter copy-ctor / atomic / pair-construction rules introduced
+# in gcc 12+ libstdc++. They compile cleanly with gcc 8 which was
+# the last major to default to C++14 / gnu++14 ABI.
+#
+# Companion to gnu.org/gcc (latest) for cubefs.io, mysql.com/v5_7,
+# and other from-source recipes that can't easily be patched to
+# modern C++.
+
+distributable:
+  url: https://ftp.gnu.org/gnu/gcc/gcc-{{ version.raw }}/gcc-{{ version.raw }}.tar.xz
+  strip-components: 1
+
+versions:
+  github: gcc-mirror/gcc/tags
+  strip: /^releases\/gcc-/
+  # Pin to the 8.x line — drop everything else.
+  ignore:
+    - /^[0-79]\./
+    - /^9\./
+    - /^[1-9][0-9]/
+
+# Linux only. Darwin's old SDK situation makes gcc 8 hard to bring
+# up — users on darwin needing legacy C++ are better off with clang
+# from llvm.org which has its own legacy mode.
+platforms:
+  - linux/x86-64
+  - linux/aarch64
+
+dependencies:
+  gnu.org/binutils: '*'
+  gnu.org/gmp: ~6
+  gnu.org/mpfr: ~4
+  gnu.org/mpc: ~1
+  zlib.net: ^1.3
+
+build:
+  dependencies:
+    linux:
+      gnu.org/gcc: '*'   # bootstrap with current gcc
+    gnu.org/make: '*'
+    perl.org: '*'
+    gnu.org/patch: '*'
+    curl.se: '*'
+    github.com/westes/flex: '*'
+
+  working-directory: build
+  script:
+    - ARGS=($ARGS --with-pkgversion="pkgx GCC {{version}}")
+    - ../configure "${ARGS[@]}"
+    - make --jobs {{ hw.concurrency }}
+    - make install
+
+    # gcc symlinks expected by some build systems. This recipe lives
+    # one level deeper than the main gnu.org/gcc (v8 subdir), so the
+    # relative path to binutils needs `../../../../` (4 levels).
+    - run: |
+        cd "{{prefix}}/bin"
+        ln -sf gcc cc
+        ln -sf ../../../../binutils/v\*/bin/ar ar
+        ln -sf ../../../../binutils/v\*/bin/nm nm
+        ln -sf ../../../../binutils/v\*/bin/ranlib ranlib
+
+  env:
+    ARGS:
+      - --prefix={{ prefix }}
+      - --libdir={{ prefix }}/lib
+      - --enable-languages=c,c++,fortran
+      - --disable-bootstrap
+      - --disable-nls
+      - --disable-multilib
+      - --with-system-zlib
+      - --with-bugurl=https://github.com/pkgxdev/pantry/issues
+    linux/x86-64:
+      LDFLAGS: -fPIC
+      CFLAGS: -fPIC
+      CXXFLAGS: -fPIC
+
+test:
+  - gcc --version | grep -q "pkgx GCC {{version}}"
+  - gcc -dumpversion | grep -q "^8\."
+
+provides:
+  - bin/ar
+  - bin/cc
+  - bin/c++
+  - bin/cpp
+  - bin/g++
+  - bin/gcc
+  - bin/gcc-ar
+  - bin/gcc-nm
+  - bin/gcc-ranlib
+  - bin/gcov
+  - bin/gfortran
+  - bin/nm
+  - bin/ranlib