Use separate output dirs for test_decoding's two runs.

contrib/test_decoding's "make check" runs two sets of tests. Unless we
specify separate output directories for each set the isolation tests
will overwrite the output from the  normal regression set. Doing this
will help the buildfarm collect complete logs.

contrib/test_decoding/Makefile

@@ -5,7 +5,7 @@ OBJS = test_decoding.o
 
 # Note: because we don't tell the Makefile there are any regression tests,
 # we have to clean those result files explicitly
-EXTRA_CLEAN = -r $(pg_regress_clean_files)
+EXTRA_CLEAN = $(pg_regress_clean_files) ./regression_output ./isolation_output
 
 ifdef USE_PGXS
 PG_CONFIG = pg_config
@@ -40,10 +40,12 @@ submake-test_decoding:
 REGRESSCHECKS=ddl rewrite toast permissions decoding_in_xact binary
 
 regresscheck: all | submake-regress submake-test_decoding
+	$(MKDIR_P) regression_output
 	$(pg_regress_check) \
 	    --temp-config $(top_srcdir)/contrib/test_decoding/logical.conf \
 	    --temp-install=./tmp_check \
 	    --extra-install=contrib/test_decoding \
+	    --outputdir=./regression_output \
 	    $(REGRESSCHECKS)
 
 regresscheck-install-force: | submake-regress submake-test_decoding
@@ -54,9 +56,11 @@ regresscheck-install-force: | submake-regress submake-test_decoding
 ISOLATIONCHECKS=mxact delayed_startup concurrent_ddl_dml
 
 isolationcheck: all | submake-isolation submake-test_decoding
+	$(MKDIR_P) isolation_output
 	$(pg_isolation_regress_check) \
 	    --temp-config $(top_srcdir)/contrib/test_decoding/logical.conf \
 	    --extra-install=contrib/test_decoding \
+	    --outputdir=./isolation_output \
 	    $(ISOLATIONCHECKS)
 
 isolationcheck-install-force: all | submake-isolation submake-test_decoding