xbps-src: multiple performance improvements

- use xbps-checkvers(1) to resolve dependencies.
- all dependencies are installed at once for the host and target.
- the show-build-deps target is now much faster.
- the update-bulk/show-repo-updates targets are now much faster.
- the update-sys/show-sys-updates targets are now much faster.
- the bootstrap target now works on musl hosts.
- simplified some loops.
- use cut(1) rather than awk(1) where applicable.
- multiple random changes to improve performance.

Based on work started by @Duncaen on #12433

Close #12433
Close #11282

.gitignore

@@ -7,3 +7,4 @@ masterdir*
 hostdir*
 etc/conf
 etc/virtual
+.xbps-checkvers.plist