Fix clang/llvm

Base for Postgres 14-18 was bumped from alpine v3.23 to v3.24 in
docker-library/official-images@769849f

Alpine v3.24 dropped support for clang19/llvm19, which caused
pgvector-build to fail for versions 14 and up.

On investigation, it turns out that it was impossible to use just one
version of clang and llvm because in alpine-12 the highest version is
still clang19.

The simplest solution is to just loop over the versions from the top down.
I even added version 23, which does not exist yet, but will defer the
necessity of doing this again for a while

Author: ljmnoonan

Dockerfile

@@ -20,8 +20,11 @@ ENV CERTS="{}" \
     HBA_EXTRA_RULES=""
 RUN apk add --no-cache python3 py3-netifaces \
  && if [ "${PG_MAJOR:-0}" -ge 12 ]; then \
-        apk add --no-cache --virtual .pgvector-build build-base clang19 llvm19 linux-headers ca-certificates; \
-        wget -qO- "https://github.com/pgvector/pgvector/archive/refs/tags/v${PGVECTOR_VERSION}.tar.gz" \
+        apk add --no-cache --virtual .pgvector-build build-base linux-headers ca-certificates \
+        && for v in 23 22 21 20 19; do \
+             apk add --no-cache --virtual .pgvector-build clang${v} llvm${v} && break; \
+           done \
+        && wget -qO- "https://github.com/pgvector/pgvector/archive/refs/tags/v${PGVECTOR_VERSION}.tar.gz" \
           | tar -xz -C /tmp; \
         cd "/tmp/pgvector-${PGVECTOR_VERSION}" \
           && make PG_CONFIG=/usr/local/bin/pg_config \