readpin: Also increase minute when the previous minute became too long.
input.c: fix bug where last0 would stay -1 when the signal would become 0 and immediately rise again.
Initialize 'sec2' once, its value will never change while running.
Explicitly check that bit.frac is valid when setting the bit value.
Revert "Initialize 'sec2' once, its value will never change while running."

This reverts commit d4e71621ddd354a1f6114e9ae7b64f3d04228f77.

It would cause sec2 to be uninitialized when init is not -1.
Found by: GCC 4.7