lang: add Hash() on bool argument

[yerden]

Hash() implementations miss the one on bool argument. That makes compilation of EqualityComparer class to fail when creating collections containing bools, as in this code:

...
Vector<bool> m_op;
...

After compilation this codes leads to:

'Hash' - ambiguous call to overloaded function	EqualityComparer.mqh	40	66

This patch fixes compilation by overloading Hash() with bool argument.

[dingmaotu]

Great fix! Thanks!