More Makefile tweaks around docker linux build.

Makefile

@@ -4,15 +4,15 @@ SOURCEFILES?=$(shell git ls-tree -r master --name-only | grep "\.hs$$")
 BRANCH?=master
 ARCH=$(shell uname -m)
 ifeq ($(ARCH),amd64)
-DOCKERIMAGE=registry.gitlab.b-data.ch/ghc/ghc4pandoc:8.10.4@sha256:83cfc60cb1df984b14d6277946002de6bc7bec25c827f5f9de3b0c5d3aeaa571
-else ifeq($(ARCH),aarch64)
-DOCKERIMAGE=registry.gitlab.b-data.ch/ghc/ghc4pandoc:8.10.4@sha256:e54a66cf8ef7f8a60b93f6a51cae7a0bd853a763098ffb3dbda2bf91b7ab49ad
+  DOCKERIMAGE=registry.gitlab.b-data.ch/ghc/ghc4pandoc:8.10.4@sha256:83cfc60cb1df984b14d6277946002de6bc7bec25c827f5f9de3b0c5d3aeaa571
+else ifeq ($(ARCH),aarch64)
+  DOCKERIMAGE=registry.gitlab.b-data.ch/ghc/ghc4pandoc:8.10.4@sha256:e54a66cf8ef7f8a60b93f6a51cae7a0bd853a763098ffb3dbda2bf91b7ab49ad
 else
-DOCKERIMAGE=UNSUPPORTEDARCHITECTURE
+  DOCKERIMAGE=UNSUPPORTEDARCHITECTURE
 endif
 COMMIT=$(shell git rev-parse --short HEAD)
 TIMESTAMP=$(shell date "+%Y%m%d_%H%M")
-LATESTBENCH=$(word 1,$(shell ls -t bench_*.csv || exit 0))
+LATESTBENCH=$(word 1,$(shell ls -t bench_*.csv 2>/dev/null))
 ifeq ($(LATESTBENCH),)
 BASELINE=
 else
@@ -91,6 +91,7 @@ debpkg: man/pandoc.1
                    -v `pwd`/linux/artifacts:/artifacts \
 		   -e REVISION=$(REVISION) \
 		   -w /mnt \
+		   --memory=0 \
 		   --rm \
 		   $(DOCKERIMAGE) \
 		   bash \