Disable temporarily TAP tests for contrib/bloom/

The recent commit 03faa4a8 has enabled those tests, however several
buildfarm members are complaining about their stability on Windows and
macOS.  This will keep the buildfarm green, while investigating the
root problem.

Discussion: https://postgr.es/m/20181126003351.GE1776@paquier.xyz

contrib/bloom/Makefile

@@ -8,7 +8,10 @@ DATA = bloom--1.0.sql
 PGFILEDESC = "bloom access method - signature file based index"
 
 REGRESS = bloom
-TAP_TESTS = 1
+
+# Disable TAP tests for this module for now, as these are unstable on several
+# platforms, including recent Windows and macOS.
+# TAP_TESTS = 1
 
 ifdef USE_PGXS
 PG_CONFIG = pg_config