fix: restore deno compile output support in alpine image

[bartlomieju]

Problem

Running the output of deno compile inside the Alpine image fails since the 2.7.8 image:

error while loading shared libraries: libdl.so.2: cannot open shared object file: No such file or directory

Fixes denoland/deno#35683.

Root cause

This is an image regression, not a deno binary bug. I confirmed the compiled binaries are identical in their ELF dependencies across versions (both need libdl.so.2, no rpath) — the difference is purely the image:

• A binary compiled by 2.7.8 runs fine on the 2.7.7 image.
• A binary compiled by 2.7.7 fails on the 2.7.8 image.

Commit 01a6547 (#523, first shipped in the 2.7.8 image) isolated glibc libs into /usr/local/lib/glibc/, dropped ENV LD_LIBRARY_PATH, and rpath-patched only /deno and /tini. A deno compile output binary gets neither the rpath nor LD_LIBRARY_PATH, so its glibc loader can't find libdl.so.2 in the isolated (non-searched) directory.

Re-adding LD_LIBRARY_PATH would reintroduce the exact musl-package conflict #523 fixed, because musl's loader also honors LD_LIBRARY_PATH and would then load the incompatible glibc libgcc_s.so.1.

Fix

Generate a glibc /etc/ld.so.cache pointing at /usr/local/lib/glibc. The glibc loader consults it, so rpath-less compiled binaries resolve their libs — while musl's loader ignores /etc/ld.so.cache entirely, so the isolation from #523 is fully preserved and no conflict returns. The cache is built with the ldconfig already present in the existing tini build stage (no new base image).

Verification (full image build, DENO_VERSION=2.9.0)

• ✅ deno runs
• ✅ deno compile output runs (the reported failure)
• ✅ apk add nodejs + node still runs — no glibc/musl conflict reintroduced