BUG/MEDIUM: htx/cache: use the correct class of error codes on abort

The HTX-specific cache code uses HTX_CACHE_* states which overlap with
the legacy HTTP states. A typo in the error handling made the state
become HTTP_CACHE_END, which equals 3 and is the value for HTX_CACHE_EOD,
which explains why we were seeing a transition to trailers and memory
corruption.

no backport needed.
diff --git a/src/cache.c b/src/cache.c
index 0d67840..c3d44f5 100644
--- a/src/cache.c
+++ b/src/cache.c
@@ -962,7 +962,7 @@
 	}
 
 	if (res->flags & (CF_SHUTW|CF_SHUTW_NOW))
-		appctx->st0 = HTTP_CACHE_END;
+		appctx->st0 = HTX_CACHE_END;
 
 	if (appctx->st0 == HTX_CACHE_INIT) {
 		appctx->ctx.cache.next = block_ptr(cache_ptr);