Closed issue by BouncyMaster on void-packages repository

https://github.com/void-linux/void-packages/issues/21808

Description:
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* system:
 `./xbps-src binary-bootstrap`
* package:  
  `mesa (20.0.6)`

### Expected behavior
Compiling mesa with `./xbps-src -o ~wayland pkg mesa`  will package the program successfully.
### Actual behavior
* The first issue is that it also packages `clang` and `llvm` when only requesting mesa.
* After compiling `clang` and `llvm` i get these errors:
```
meson.build:306:4: ERROR: Problem encountered: Invalid argument list given to -Dplatforms
and
ERROR:   in do_configure() at common/build-style/meson.sh:95
```
There were more errors but they were obstructed when i accidentaly resized the terminal.

Output of `/builddir/mesa-20.0.6/build/meson-logs/meson-log.txt`
[meson-log.txt](https://github.com/void-linux/void-packages/files/4605401/meson-log.txt)

Also there is my etc/conf:
```
XBPS_CFLAGS="-O2 -march=znver1 -pipe"
XBPS_CXXFLAGS="${XBPS_CFLAGS}"
```