Fix warnings for functions and blocks with no parameters

[adimango]

The SDK has several warnings linked to the declaration of fuction and block with no parameters.

This error occurs when you try to declare a function with no arguments, and compile with -Werror=strict-prototypes, as follows:

int foo();

Fix it by declare it as

int foo(void);

This is because in c, foo(void) takes no arguments while foo() takes a infinite number of arguments.

The same, when declaring blocks with no parameters:

Fixed it by declaring it as

void (^)(void)