Install MCPL using same build type as OpenMC in CI (#3388)

CMakeLists.txt

@@ -194,6 +194,13 @@ endif()
 #===============================================================================
 
 if (OPENMC_USE_MCPL)
+  if (NOT DEFINED MCPL_DIR)
+    execute_process(
+      COMMAND mcpl-config --show cmakedir
+      OUTPUT_VARIABLE MCPL_DIR
+      OUTPUT_STRIP_TRAILING_WHITESPACE
+    )
+  endif()
   find_package(MCPL REQUIRED)
   message(STATUS "Found MCPL: ${MCPL_DIR} (found version \"${MCPL_VERSION}\")")
 endif()

cmake/OpenMCConfig.cmake.in

@@ -30,7 +30,7 @@ if(@OPENMC_USE_OPENMP@)
 endif()
 
 if(@OPENMC_USE_MCPL@)
-  find_package(MCPL REQUIRED)
+  find_package(MCPL REQUIRED HINTS @MCPL_DIR@)
 endif()
 
 if(@OPENMC_USE_UWUW@ AND NOT ${DAGMC_BUILD_UWUW})

tools/ci/gha-install-mcpl.sh

@@ -1,7 +0,0 @@
-#!/bin/bash
-set -ex
-cd $HOME
-git clone https://github.com/mctools/mcpl
-cd mcpl
-mkdir build && cd build
-cmake .. && make 2>/dev/null && sudo make install

tools/ci/gha-install.sh

@@ -29,7 +29,7 @@ if [[ $LIBMESH = 'y' ]]; then
 fi
 
 # Install MCPL
-./tools/ci/gha-install-mcpl.sh
+pip install mcpl
 
 # For MPI configurations, make sure mpi4py and h5py are built against the
 # correct version of MPI