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/hydra-queue-runner/Makefile.am

@@ -1,8 +0,0 @@
-bin_PROGRAMS = hydra-queue-runner
-
-hydra_queue_runner_SOURCES = hydra-queue-runner.cc queue-monitor.cc dispatcher.cc \
- builder.cc build-result.cc build-remote.cc \
- hydra-build-result.hh counter.hh state.hh db.hh \
- nar-extractor.cc nar-extractor.hh
-hydra_queue_runner_LDADD = $(NIX_LIBS) -lpqxx -lprometheus-cpp-pull -lprometheus-cpp-core
-hydra_queue_runner_CXXFLAGS = $(NIX_CFLAGS) -Wall -I ../libhydra -Wno-deprecated-declarations

src/hydra-queue-runner/meson.build

@@ -0,0 +1,22 @@
+srcs = files(
+  'builder.cc',
+  'build-remote.cc',
+  'build-result.cc',
+  'dispatcher.cc',
+  'hydra-queue-runner.cc',
+  'nar-extractor.cc',
+  'queue-monitor.cc',
+)
+
+hydra_queue_runner = executable('hydra-queue-runner',
+  'hydra-queue-runner.cc',
+  srcs,
+  dependencies: [
+    libhydra_dep,
+    nix_dep,
+    pqxx_dep,
+    prom_cpp_core_dep,
+    prom_cpp_pull_dep,
+  ],
+  install: true,
+)