New comment by ericonr on void-packages repository

https://github.com/void-linux/void-packages/pull/28657#issuecomment-777093539

Comment:
```
# Used by the gstutils test
gmp_dep = cc.find_library('gmp', required : false)
cdata.set('HAVE_GMP', gmp_dep.found())
gsl_dep = cc.find_library('gsl', required : false)
gslcblas_dep = cc.find_library('gslcblas', required : false)
cdata.set('HAVE_GSL', gsl_dep.found() and gslcblas_dep.found())
test_deps = [gmp_dep, gsl_dep, gslcblas_dep]
```

These are test dependencies only. Might make sense to add to `checkdepends`, I guess.