meson: Fix build of static plugins

While we were correctly skipping the plugins that couldn't be
built statically, we were still adding their names to the list
and the .pc list causing them to still get built.

Part-of: <https://gitlab.freedesktop.org/gstreamer/gst-plugins-rs/-/merge_requests/994>

ci/generate-static-test.py

@@ -7,7 +7,7 @@ import os
 from utils import iterate_plugins
 
 # the csound version used on ci does not ship a .pc file
-IGNORE = ['csound']
+IGNORE = ['csound', 'threadshare']
 
 outdir = sys.argv[1]
 

meson.build

@@ -282,7 +282,6 @@ foreach plugin : plugins
     warning('Static plugin @0@ is known to fail. It will not be included in libgstreamer-full.'.format(plugin_name))
   else
     gst_plugins += dep
-  endif
 
     pc_files += [plugin_name + '.pc']
     if plugin_name.startswith('gst')
@@ -290,6 +289,7 @@ foreach plugin : plugins
     else
       plugin_names += [plugin_name]
     endif
+  endif
 endforeach
 
 subdir('docs')