Make build prefix configurable in the Dockerfile

Allows passing --build-arg=/some/prefix to cmake when building the
image. The immediate need will be in the next commit, but there are
other potential uses like building an actual system rpm in the image
(ie with the original prefix) or randomizing the prefix to make sure
no hardcoded assumptions end up in the tests etc.

Author: pmatilai

tests/Dockerfile.fedora

@@ -1,3 +1,5 @@
+ARG PREFIX=/usr/local
+
 # Supported Fedora releases: 40 41
 FROM registry.fedoraproject.org/fedora:41 AS base
 MAINTAINER [email protected]
@@ -88,6 +90,7 @@ WORKDIR /
 CMD /bin/bash
 
 FROM base AS full
+ARG PREFIX
 
 WORKDIR /srv/rpm
 COPY . .
@@ -106,6 +109,7 @@ RUN cmake \
 	-DWITH_DOXYGEN=ON \
 	-DENABLE_TESTSUITE=ON \
 	-DMKTREE_BACKEND=rootfs \
+	-DCMAKE_INSTALL_PREFIX=${PREFIX} \
 	../rpm
 RUN make -j$(nproc) tree
 

tests/mktree.oci

@@ -26,7 +26,7 @@ else
 fi
 
 IMAGE=rpm
-ARGS="-f Dockerfile $FROM $CONTEXT"
+ARGS="-f Dockerfile $FROM $CONTEXT "
 ROOTLESS=$([ $(id -u) == 0 ] && echo 0 || echo 1)
 CMD=$1; shift