Still read config file from Library/Preferences if it exists

[glandium]

Fixes #919

[glandium]

@mstange Can you double check that this uses a config from ~/Library/Preferences if you move it back there?

[mstange]

I will check tomorrow.

Looking at the patch, I think that if both files are present, the patch prefers the one in Preferences. I think it would be better to prefer the one in the new location.

[mitchhentges]

Looks good, but I agree with :mstange's suggestion on prioritizing our new config path first.

[mstange]

@mstange Can you double check that this uses a config from ~/Library/Preferences if you move it back there?

Confirmed, the patch works.

% cargo build --features "all native-zlib" --release
[...]
% mv ~/Library/Application\ Support/Mozilla.sccache/config ~/Library/Preferences/Mozilla.sccache/
% SCCACHE_LOG=trace ./target/release/sccache --dist-status
[...]
[2021-01-06T17:23:37Z DEBUG sccache::config] Attempting to read config file at "/Users/mstange/Library/Preferences/Mozilla.sccache/config"
[...]
{"SchedulerStatus":["http://192.168.2.146:10600/",{"num_servers":1,"num_cpus":16,"in_progress":0}]}%