build: Support the meson build system

Meson is on track to replace autotools as the build system of choice,
so support it in addition to autotools. If all goes well, we'll
eventually be able to drop the latter ...

https://bugzilla.gnome.org/show_bug.cgi?id=783229

browser-plugin/meson.build

@@ -0,0 +1,19 @@
+plugin_sources = [
+  'browser-plugin.c',
+  'npapi/npapi.h',
+  'npapi/npfunctions.h',
+  'npapi/npruntime.h',
+  'npapi/nptypes.h'
+]
+
+shared_module('gnome-shell-browser-plugin', plugin_sources,
+  dependencies: [gio_dep, json_glib_dep],
+  c_args: ['-DG_LOG_DOMAIN="GnomeShellBrowserPlugin"'],
+  # Browsers can unload and reload the module while browsing, which is not
+  # supported by GObject.
+  # We pass -Wl,-z,nodelete to the linker to ensure the module is never
+  # unloaded. See https://bugzilla.gnome.org/show_bug.cgi?id=737932.
+  link_args: ['-Wl,-z,nodelete'],
+  install: true,
+  install_dir: plugindir
+)