Force alignment on arm32

This fixes our test failures on Debian-based arm32v7, and fixes *most* of our test failures on Alpine-based arm32v{6,7}, leaving the notable `t/restart.t` which we've had issues with prior.

Author: tianon

1/alpine/Dockerfile

@@ -90,6 +90,18 @@ RUN set -eux; \
 {{ ) else "" end -}}
 	cd /usr/src/memcached; \
 	\
+# https://github.com/memcached/memcached/issues/1220#issuecomment-2770251664: on arm32, we need to override the upstream alignment check (which fails to detect the need for alignment on arm32v6+ on our hardware for some reason, which then causes us to fail the tests 😭)
+	arch="$({{
+		{
+			"alpine": "apk --print-arch",
+			"debian": "dpkg --print-architecture",
+		}[env.variant]
+		// error("unknown variant: \(env.variant)")
+	}})"; \
+	case "$arch" in \
+		armhf | armv7) export ac_cv_c_alignment=need ;; \
+	esac; \
+	\
 	gnuArch="$(dpkg-architecture --query DEB_BUILD_GNU_TYPE)"; \
 	./configure \
 		--build="$gnuArch" \