proof: do not regenerate par files if they are up to date

proof/proofbench/CMakeLists.txt

@@ -31,19 +31,24 @@ ROOT_STANDARD_LIBRARY_PACKAGE(ProofBench
 
 # Generation and installation of the PAR files required by the benchmark
 add_custom_target(ProofBenchPARFiles ALL
+  DEPENDS
+    ${CMAKE_BINARY_DIR}/etc/proof/proofbench/ProofBenchCPUSel.par
+    ${CMAKE_BINARY_DIR}/etc/proof/proofbench/ProofBenchDataSel.par
+)
+
+add_custom_command(OUTPUT
+    ${CMAKE_BINARY_DIR}/etc/proof/proofbench/ProofBenchCPUSel.par
+    ${CMAKE_BINARY_DIR}/etc/proof/proofbench/ProofBenchDataSel.par
   DEPENDS
     ${CMAKE_SOURCE_DIR}/etc/proof/utils/makepbenchpars.sh
+  COMMAND
+    ${CMAKE_COMMAND} -E make_directory ${CMAKE_BINARY_DIR}/etc/proof/proofbench
   COMMAND
     ${CMAKE_SOURCE_DIR}/etc/proof/utils/makepbenchpars.sh ProofBenchCPUSel ${CMAKE_SOURCE_DIR} ${CMAKE_BINARY_DIR}
   COMMAND
     ${CMAKE_SOURCE_DIR}/etc/proof/utils/makepbenchpars.sh ProofBenchDataSel ${CMAKE_SOURCE_DIR} ${CMAKE_BINARY_DIR}
-  BYPRODUCTS
-    ${CMAKE_BINARY_DIR}/etc/proof/proofbench/ProofBenchCPUSel.par
-    ${CMAKE_BINARY_DIR}/etc/proof/proofbench/ProofBenchDataSel.par
   WORKING_DIRECTORY ${CMAKE_SOURCE_DIR}
 )
 
-add_dependencies(ProofBenchPARFiles move_artifacts)
-
 install(DIRECTORY ${CMAKE_BINARY_DIR}/etc/proof/proofbench
         DESTINATION ${CMAKE_INSTALL_SYSCONFDIR}/proof USE_SOURCE_PERMISSIONS)