only dlopen from the defined search paths

Don't accept absolute library paths that are not in the search path,
skip the ../ in paths to avoid opening arbitrary libraries from
unexpected places.

src/daemon/filter-chain/source-rnnoise.conf

@@ -21,7 +21,6 @@ context.modules = [
 			# listed in the environment variable LADSPA_PATH or 
 			# /usr/lib64/ladspa, /usr/lib/ladspa or the system library directory
 			# as a fallback.
-			# You might want to use an absolute path here to avoid problems.
                         plugin = "librnnoise_ladspa"
                         label  = noise_suppressor_stereo
                         control = {