Activating plumed do not need an extra cached variable anymore

As we discussed in #5292, I modified how `gmx_manage_plumed` activates the plumed module and moved where it is called.

Author: Daniele

cmake/gmxManagePlumed.cmake

@@ -48,7 +48,7 @@ mark_as_advanced(GMX_USE_PLUMED)
 function(gmx_manage_plumed)
     # Create a link target, leave it empty if the plumed option is not active
     add_library(plumedgmx INTERFACE)
-    set (GMX_PLUMED_ACTIVE OFF CACHE INTERNAL "Cache entry for PLUMED activation")
+    set (GMX_PLUMED_ACTIVE OFF PARENT_SCOPE)
     if(WIN32)
         if(GMX_USE_PLUMED STREQUAL "ON")
                 message(FATAL_ERROR "PLUMED is not supported on Windows. Reconfigure with -DGMX_USE_PLUMED=OFF.")
@@ -67,7 +67,7 @@ function(gmx_manage_plumed)
             target_link_libraries( plumedgmx INTERFACE ${CMAKE_DL_LIBS} )
             # The plumedgmx already exists, now we set it up:
             target_include_directories(plumedgmx SYSTEM INTERFACE $<BUILD_INTERFACE:${PLUMED_DIR}>)
-            set (GMX_PLUMED_ACTIVE ON CACHE INTERNAL "Cache entry for PLUMED activation")
+            set (GMX_PLUMED_ACTIVE ON PARENT_SCOPE)
         else()
             if(GMX_USE_PLUMED STREQUAL "ON")
                 message(FATAL_ERROR "PLUMED needs dlopen or anything equivalent. Reconfigure with -DGMX_USE_PLUMED=OFF.")

src/gromacs/CMakeLists.txt

@@ -68,6 +68,10 @@ mark_as_advanced(GMX_USE_SIMD_KERNELS)
 # pulling is using the muparser target as well, so detect it early
 gmx_manage_muparser()
 
+# The following functions and macros called here sets up the "module_x_active" variable before
+# including the directories with their own modules
+gmx_manage_plumed()
+
 # Add these contents first because linking their tests can take a lot
 # of time, so we want lots of parallel work still available after
 # linking starts.
@@ -450,7 +454,6 @@ target_link_libraries(libgromacs PRIVATE lmfit)
 target_link_libraries(libgromacs PRIVATE muparser::muparser)
 gmx_manage_colvars()
 target_link_libraries(libgromacs PRIVATE colvars)
-gmx_manage_plumed()
 target_link_libraries(libgromacs PRIVATE plumedgmx)
 
 # Make sure we fix "everything" found by compilers that support that