uhd: paths: Harmonize around XDG Base Directory specification

Up until now, we completely ignore the XDG specification.

This commit does the following to change that:

- It uses XDG_DATA_HOME and XDG_CONFIG_HOME for cal and config data,
  respectively.
- If config data is in ~/.uhd/uhd.conf, that is still accepted, but if
  it conflicts with $XDG_CONFIG_HOME/uhd.conf, it is ignored and a
  warning is displayed
- The default location for cal data is thus ${HOME}/.local/share/uhd/cal
  on Unix, and %LOCALAPPDATA%\uhd\cal on Windows. This is a change in
  location!
- The UHD_CONFIG_DIR environment variable was confusingly named and is
  now removed. It provided an alternative location than the home
  directory. The same purpose is now much better served by XDG_DATA_HOME
  and XDG_CONFIG_HOME.

The specification can be found here:
specifications.freedesktop.org/basedir-spec/basedir-spec-latest.html

1 files changed, 0 insertions, 3 deletions

diff --git a/host/include/uhd/utils/paths.hpp b/host/include/uhd/utils/paths.hpp
index f55f584a5..8bcf22171 100644
--- a/host/include/uhd/utils/paths.hpp
+++ b/host/include/uhd/utils/paths.hpp
@@ -20,9 +20,6 @@ namespace uhd {
 //! Get a string representing the system's temporary directory
 UHD_API std::string get_tmp_path(void);
 
-//! Get a string representing the system's appdata directory
-UHD_API std::string get_app_path(void);
-
 //! Get a string representing the system's library directory
 UHD_API std::string get_lib_path(void);