Just like everybody has told you, you cannot detect that the LED is blinking. It is blinking though but you won't notice it.
You can go with post #3 but the LED will be toggled after every 5 seconds. If that time is too long for the LED to stay ON, then you can edit Line 27 to be:
elsif count = (50000000-1) then
Also insert between lines 29 and 30:
else count <= count+1;
This will make the LED to stay ON for 1 second and OFF for 4 seconds. But it will light up the first time after 5 seconds. If you need another ON time duration, you can figure out the value that would make that happen and use that in place of the 50000000 that would now be in line 27.
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Add:
If you want OFF time to be 5 seconds and ON time to be x seconds then you have to increase your LED cycle period from 5 seconds to (5+x) seconds.