bug#49460: links not clickable in some qt programs (nheko, quaternion)

[Hamzeh Nasajpour]

I have the same issue with all of Qt applications that are using 
`QDesktopServices::openUrl(...)`. I developed some applications that are using 
this method of Qt. In all of them I get this error when I want to open links:

```
Launch failed 
(/gnu/store/bi4m86lripz4fhhi4c34ylg5ckxsrqzs-xdg-utils-1.1.3/bin/xdg-open ....)
```

The current `xdg-utils` path in my store is:
```
/gnu/store/0zdclmgw5gnpifwb7jyrmplrk13wp0yz-xdg-utils-1.1.3/
```

This is the references of my application by `guix gc`:
```
$ guix gc --references 
/gnu/store/dyrg1naixia5w4qg9d1mj8smi1lyww2n-px-software-0.3.3/
/gnu/store/01b4w3m6mp55y531kyi1g8shh722kwqm-gcc-7.5.0-lib
/gnu/store/2ql96jy3ilx219ddra32a6bdm8abzpzg-yaml-cpp-0.6.3
/gnu/store/6l9rix46ydxyldf74dvpgr60rf5ily0c-guile-3.0.7
/gnu/store/cfzp7ab58whr1jb5k64c0anc8cnv42x4-recutils-1.8
/gnu/store/dyrg1naixia5w4qg9d1mj8smi1lyww2n-px-software-0.3.3
/gnu/store/fa6wj5bxkj5ll1d7292a70knmyl7a0cr-glibc-2.31
/gnu/store/nrv3frmd7i0fqprmd7br6jhknhbx75fr-qtbase-5.15.2
/gnu/store/rykm237xkmq7rl1p0nwass01p090p88x-zlib-1.2.11
/gnu/store/zjb18dwpbcsqdgjq1fsfx8xnpywzkj2c-px-gui-library-0.1.7
```

I think the wrong path will be set here: 
https://git.savannah.gnu.org/cgit/guix.git/tree/gnu/packages/qt.scm#n442

I don't know why and where this wrong `xdg-utils` path come in.


--

Hamzeh Nasajpour
PantherX Team