Remove unused macros from C headers

After grep-ing the code, I haven't found a single instance of them being used.
They look like being phased out a long time ago.

Also: It would be of if I removed other strange chunks of code? Because I found this, and it's actually used in a few places in the library.
```
#define OPENCV_CALL( Func )                                         \
{                                                                   \
Func;                                                           \
}
```