[CMake] Enforce conan supplied mfront.

Fixes #3034.

CMakeLists.txt

@@ -263,6 +263,12 @@ if(EXISTS ${PROJECT_SOURCE_DIR}/ThirdParty/vtkdiff/CMakeLists.txt AND BUILD_TEST
     install(PROGRAMS $<TARGET_FILE:vtkdiff> DESTINATION bin COMPONENT ogs_extras)
 endif()
 
+# Correct tfel paths (they seem to be hard-coded to /usr/local/tfel/...)
+if(OGS_USE_MFRONT AND OGS_USE_CONAN)
+    set(TFEL_INCLUDE_PATH "${CONAN_TFEL_ROOT}/include")
+    set(TFEL_LIBRARY_PATH "${CONAN_TFEL_ROOT}/lib")
+endif()
+
 include(scripts/cmake/CheckHeaderCompilation.cmake)
 
 add_subdirectory(Applications)

scripts/cmake/Find.cmake

@@ -90,6 +90,9 @@ if(OGS_USE_MFRONT)
         set(HAVE_PTHREADS TRUE)
         add_definitions(-DHAVE_PTHREADS)
     endif()
+    if(OGS_USE_CONAN)
+        set(TFEL_INSTALL_PATH ${CONAN_TFEL_ROOT} CACHE INTERNAL "")
+    endif()
 endif()
 
 # Do not search for libs if this option is set