Make it running on Fedora

 - fixes CRaC#4
 - I understand it is not an acceptable platform-agnostic fix

Dockerfile.baseline

@@ -1,4 +1,4 @@
-FROM ubuntu:18.04
+FROM fedora
 
 COPY jdk /jdk
 

Dockerfile.checkpoint

@@ -1,9 +1,8 @@
-FROM ubuntu:18.04 as builder
+FROM fedora as builder
 
-RUN apt update && \
-	DEBIAN_FRONTEND=noninteractive apt -y --no-install-recommends install liblz4-tool && \
-	apt clean && \
-	rm -rf /var/lib/apt /var/cache/apt
+RUN dnf -y update && \
+	dnf -y install lz4 && \
+	dnf clean all
 
 COPY jdk /jdk
 
@@ -13,12 +12,11 @@ RUN LIBJVM=/jdk/lib/server/libjvm.so; \
 	       ln -s /tmp/sub/$LIBJVM $LIBJVM
 
 
-FROM ubuntu:18.04
+FROM fedora
 
-RUN apt update && \
-	DEBIAN_FRONTEND=noninteractive apt -y --no-install-recommends install liblz4-tool && \
-	apt clean && \
-	rm -rf /var/lib/apt /var/cache/apt
+RUN dnf -y update && \
+	dnf -y install lz4 && \
+	dnf clean all
 
 COPY --from=builder /jdk /jdk
 COPY prepare-jdk.cmd.sh /

Dockerfile.restore

@@ -1,9 +1,8 @@
-FROM ubuntu:18.04 as builder
+FROM fedora as builder
 
-RUN apt update && \
-	DEBIAN_FRONTEND=noninteractive apt -y --no-install-recommends install liblz4-tool && \
-	apt clean && \
-	rm -rf /var/lib/apt /var/cache/apt
+RUN dnf -y update && \
+	dnf -y install lz4 && \
+	dnf clean all
 
 COPY cr /cr
 RUN tar -c /cr | lz4 -z -9 - /cr.tar.lz4