internal/rosa/cmake: use DESTDIR instead of --prefix

Turns out --prefix is deeply broken, and DESTDIR works even when using ninja.

Signed-off-by: Ophestra <cat@gensokyo.uk>

internal/rosa/cmake.go

@@ -98,6 +98,6 @@ cmake -G ` + generate + ` \
 	-DCMAKE_INSTALL_PREFIX=/system \
 	'/usr/src/` + name + `/` + filepath.Join(attr.Append...) + `'
 cmake --build . --parallel=` + jobsE + `
-cmake --install . --prefix=/work/system
+DESTDIR=/work cmake --install .
 ` + script
 }