meson: Fix typo in gsm header file name
This was wrong since commit c360ceea.
Also fix incorrect indentation (tab instead of spaces).
Found using hermetic builds with Nix:
https://github.com/NixOS/nixpkgs/pull/54398#discussion_r280125735
This was wrong since commit c360ceea.
Also fix incorrect indentation (tab instead of spaces).
Found using hermetic builds with Nix:
https://github.com/NixOS/nixpkgs/pull/54398#discussion_r280125735