autotools -> meson

Original commit message:

> There are some known regressions regarding local testing setups - since
> everything was kinda half written with the expectation that build dir =
> source dir (which should not be true anymore). But everything builds and
> the test suite runs fine, after several hours spent debugging random
> crashes in libpqxx with MALLOC_PERTURB_...

I have not experienced regressions with local testing.

(cherry picked from commit 4b886d9c45cd2d7fe9b0a8dbc05c7318d46f615d)

src/script/Makefile.am

@@ -1,19 +0,0 @@
-EXTRA_DIST =					\
-  $(distributable_scripts)
-
-distributable_scripts =				\
-  hydra-backfill-ids				\
-  hydra-init					\
-  hydra-eval-jobset				\
-  hydra-server					\
-  hydra-update-gc-roots				\
-  hydra-s3-backup-collect-garbage		\
-  hydra-create-user				\
-  hydra-notify					\
-  hydra-send-stats				\
-  nix-prefetch-git				\
-  nix-prefetch-bzr				\
-  nix-prefetch-hg
-
-bin_SCRIPTS =					\
-  $(distributable_scripts)