build: link against the gnustl dependency on android for c++ plugins

ext/soundtouch/meson.build

@@ -9,6 +9,10 @@ if get_option('soundtouch').disabled()
   subdir_done()
 endif
 
+if not gnustl_dep.found() and get_option('soundtouch').enabled()
+  error('soundtouch plugin enabled but could not find gnustl dep for Android c++ support')
+endif
+
 soundtouch_dep = dependency('soundtouch', required : false)
 if soundtouch_dep.found()
   soundtouch_cargs += ['-DHAVE_SOUNDTOUCH_1_4']
@@ -32,7 +36,7 @@ if soundtouch_dep.found()
     c_args : gst_plugins_bad_args + soundtouch_cargs,
     cpp_args : gst_plugins_bad_args + soundtouch_cargs,
     include_directories : [configinc],
-    dependencies : [gstaudio_dep, soundtouch_dep],
+    dependencies : [gstaudio_dep, soundtouch_dep, gnustl_dep],
     install : true,
     install_dir : plugins_install_dir)
   pkgconfig.generate(gstsoundtouch, install_dir : plugins_pkgconfig_install_dir)

ext/webrtcdsp/meson.build

@@ -6,9 +6,8 @@ webrtc_sources = [
 webrtc_dep = dependency('webrtc-audio-processing', version : ['>= 0.2', '< 0.4'],
                         required : get_option('webrtcdsp'))
 
-gnustl_dep = declare_dependency()
-if host_system == 'android'
-  gnustl_dep = dependency('gnustl', required : get_option('webrtcdsp'))
+if not gnustl_dep.found() and get_option('webrtcdsp').enabled()
+  error('webrtcdsp plugin enabled but could not find gnustl dep for Android c++ support')
 endif
 
 if webrtc_dep.found() and gnustl_dep.found()

meson.build

@@ -499,6 +499,11 @@ else
   cdata.set('DISABLE_ORC', 1)
 endif
 
+gnustl_dep = declare_dependency()
+if host_system == 'android'
+  gnustl_dep = dependency('gnustl', required : false)
+endif
+
 if gst_dep.type_name() == 'internal'
   gst_debug_disabled = not subproject('gstreamer').get_variable('gst_debug')
 else