COMP: Use exec_program instead of execute_process

Tests/SimpleExclude/run.cmake.in

@@ -1,11 +1,9 @@
 set(t4_name "@CMAKE_CURRENT_BINARY_DIR@${CFG_DIR}/t4")
-execute_process(COMMAND "${t4_name}"
-  RESULT_VARIABLE "t4_var")
+exec_program("${t4_name}" RETURN_VALUE "t4_var")
 message("T4 ${t4_name} resulted ${t4_var}")
 
 set(t9_name "@CMAKE_CURRENT_BINARY_DIR@${CFG_DIR}/t9")
-execute_process(COMMAND "${t9_name}"
-  RESULT_VARIABLE "t9_var")
+exec_program("${t9_name}" RETURN_VALUE "t9_var")
 message("T9 ${t9_name} resulted ${t9_var}")
 
 if ( "${t4_var}" EQUAL "0" AND "${t9_var}" EQUAL "0" )