C/C++: correct indentation for control statements (if/for/while) without braces

[wojdyr]

Currently, as discussed in #21161, having a statement such as

while (something)

doesn't increase indentation in the next line.

It might have something to do with simplistic cpp/indents.scm.

This was partly fixed for C (for if and for only):
9296159#diff-f8e4cb54de4d2596440eb20f78fec8bbf16f6ee540a5250b893075327240448d

For comparison, here are similar files for neovim:
https://github.com/nvim-treesitter/nvim-treesitter/blob/master/queries/c/indents.scm
https://github.com/nvim-treesitter/nvim-treesitter/blob/master/queries/cpp/indents.scm

My guess is that if you replace the content of cpp/indents.scm with:

; inherits: c

it will bring C++ indentation on par with C indentation (ifs and fors are most common).