host_applications/linux/apps/hello_pi/hello_fft/mailbox.h: remove declaration of get_version?

[nubok]

Describe the bug

The file mailbox.h of the hello_fft application

https://github.com/raspberrypi/userland/blob/3fd8527eefd8790b4e8393458efc5f94eb21a615/host_applications/linux/apps/hello_pi/hello_fft/mailbox.h

contains a declaration

unsigned get_version(int file_desc);

This declaration is used nowhere in the code. In particular

https://github.com/raspberrypi/userland/blob/3fd8527eefd8790b4e8393458efc5f94eb21a615/host_applications/linux/apps/hello_pi/hello_fft/mailbox.c

does not contain an implementation of this function.

Expected behaviour

I would expect that either

1. mailbox.c contains an implementation of get_version or
2. the declaration of get_version is removed from mailbox.h since no implementation of it exits.

If it is decided to choose 1., it would make sense that get_version is used in hello_fft (https://github.com/raspberrypi/userland/tree/3fd8527eefd8790b4e8393458efc5f94eb21a615/host_applications/linux/apps/hello_pi/hello_fft).

Actual behaviour

See section "Describe the bug".

[popcornmix]

Removed the unused declaration from internal repo. Will appear in userland next firmware build.

[popcornmix]

Userland updated.