If we use a --docdir that's not specific to the package, then different builds
will install their license files into the same location, which leads to file
collisions if those are ever joined into the same environment.
Fixes https://github.com/NixOS/nixpkgs/issues/35024.
The stable build for `yabar` is currently broken: https://hydra.nixos.org/build/75989172
Main reason is that the inline function `ya_setup_prefix_suffix` is
supposed to be an inline function, but was insufficiently declared as
such which broke the compiler recently with the following message:
```
gcc -std=c99 -Iinclude -pedantic -Wall -Os `pkg-config --cflags pango pangocairo libconfig` -DVERSION=\"0.4.0\" -D_POSIX_C_SOURCE=199309L -DYA_INTERNAL -DYA_DYN_COL -DYA_ENV_VARS -DYA_INTERNAL_EWMH -c -o src/intern_blks/ya_intern.o src/intern_blks/ya_intern.c
gcc -o yabar src/ya_main.o src/ya_draw.o src/ya_exec.o src/ya_parse.o src/intern_blks/ya_intern.o -lxcb -lpthread -lxcb-randr -lxcb-ewmh `pkg-config --libs pango pangocairo libconfig`
src/intern_blks/ya_intern.o: In function `ya_int_date':
ya_intern.c:(.text+0x49): undefined reference to `ya_setup_prefix_suffix'
src/intern_blks/ya_intern.o: In function `ya_int_uptime':
ya_intern.c:(.text+0xf4): undefined reference to `ya_setup_prefix_suffix'
src/intern_blks/ya_intern.o: In function `ya_int_brightness':
ya_intern.c:(.text+0x1d8): undefined reference to `ya_setup_prefix_suffix'
src/intern_blks/ya_intern.o: In function `ya_int_bandwidth':
ya_intern.c:(.text+0x377): undefined reference to `ya_setup_prefix_suffix'
src/intern_blks/ya_intern.o: In function `ya_int_cpu':
ya_intern.c:(.text+0x6de): undefined reference to `ya_setup_prefix_suffix'
src/intern_blks/ya_intern.o:ya_intern.c:(.text+0x924): more undefined references to `ya_setup_prefix_suffix' follow
collect2: error: ld returned 1 exit status
make: *** [Makefile:18: yabar] Error 1
```
This issue has been fixed on master (see
https://github.com/geommer/yabar/commit/9779a5e04bd6e8cdc1c9fcf5d7ac31416af85a53)
which is why `nixos.yabar-unstable` remained functional.
This is the newest sdk. I have skipped 9.3 for now but someone can
certainly add it if they need it for some reason.
Also I added a generic "xcode" that will always point to the newest
xcode that is available in Nixpkgs.
Claas Augner