[cmake][bugfix] correctly pipe form compiler args

cmake/modules/DunePerftoolMacros.cmake

@@ -64,12 +64,12 @@ file(GLOB_RECURSE UFL2PDELAB_SOURCES ${UFL2PDELAB_GLOB_PATTERN})
 function(add_generated_executable)
   set(OPTIONS)
   set(SINGLE TARGET OPERATOR DRIVER UFLFILE)
-  set(MULTI FORM_COMPILER_FLAGS)
+  set(MULTI FORM_COMPILER_ARGS)
   include(CMakeParseArguments)
   cmake_parse_arguments(GEN "${OPTIONS}" "${SINGLE}" "${MULTI}" ${ARGN})
 
   if(GEN_UNPARSED_ARGUMENTS)
-    message("Unrecognized arguments in add_generated_executable. This usually indicates a typo.")
+    message(FATAL_ERROR "Unrecognized arguments in add_generated_executable. This usually indicates a typo.")
   endif()
 
   # Apply defaults and enforce requirements