meson: introduce mesonInstallTags

Projects building with meson are currently installTargets. Map these
to install tags, which are roughly equivalent. This allows projects to
selectively install components.

doc/hooks/meson.section.md

@@ -43,3 +43,12 @@ Disables using Meson’s `checkPhase`.
 ### `dontUseMesonInstall` {#dontusemesoninstall}
 
 Disables using Meson’s `installPhase`.
+
+### `mesonInstallFlags` {#mesoninstallflags}
+
+Controls the flags passed to meson install.
+
+### `mesonInstallTags` (#mesoninstalltags)
+
+Tags specified here will be passed to Meson as via `--tags` during
+installation and controls which components will be installed.

pkgs/development/tools/build-managers/meson/setup-hook.sh

@@ -55,6 +55,10 @@ mesonInstallPhase() {
     # shellcheck disable=SC2086
     local flagsArray=($mesonInstallFlags "${mesonInstallFlagsArray[@]}")
 
+    if [[ -n "$mesonInstallTags" ]]; then
+        flagsArray+=("--tags" "${mesonInstallTags// /,}")
+    fi
+
     echoCmd 'install flags' "${flagsArray[@]}"
     meson install --no-rebuild "${flagsArray[@]}"