lv2: Make it build with -fno-common

GCC 10 defaults to -fno-common. This means that global variables shared
across multiple translation units should be declared as 'extern' in
header files and defined in exactly one C file. See:
https://gcc.gnu.org/gcc-10/porting_to.html

https://gitlab.freedesktop.org/gstreamer/gst-plugins-bad/-/merge_requests/1125

Part-of: <https://gitlab.freedesktop.org/gstreamer/gst-plugins-bad/-/merge_requests/1609>

2 files changed, 64 insertions, 31 deletions

diff --git a/ext/lv2/gstlv2.c b/ext/lv2/gstlv2.c
index 705c4d404..4c6601f4f 100644
--- a/ext/lv2/gstlv2.c
+++ b/ext/lv2/gstlv2.c
@@ -69,6 +69,39 @@ GST_DEBUG_CATEGORY (lv2_debug);
 #error "Unsupported OS"
 #endif
 
+LilvWorld *world = NULL;
+LilvNode *atom_class = NULL;
+LilvNode *audio_class = NULL;
+LilvNode *control_class = NULL;
+LilvNode *cv_class = NULL;
+LilvNode *event_class = NULL;
+LilvNode *input_class = NULL;
+LilvNode *output_class = NULL;
+LilvNode *preset_class = NULL;
+LilvNode *state_iface = NULL;
+LilvNode *state_uri = NULL;
+
+LilvNode *integer_prop = NULL;
+LilvNode *toggled_prop = NULL;
+LilvNode *designation_pred = NULL;
+LilvNode *in_place_broken_pred = NULL;
+LilvNode *optional_pred = NULL;
+LilvNode *group_pred = NULL;
+LilvNode *supports_event_pred = NULL;
+LilvNode *label_pred = NULL;
+
+LilvNode *center_role = NULL;
+LilvNode *left_role = NULL;
+LilvNode *right_role = NULL;
+LilvNode *rear_center_role = NULL;
+LilvNode *rear_left_role = NULL;
+LilvNode *rear_right_role = NULL;
+LilvNode *lfe_role = NULL;
+LilvNode *center_left_role = NULL;
+LilvNode *center_right_role = NULL;
+LilvNode *side_left_role = NULL;
+LilvNode *side_right_role = NULL;
+
 GstStructure *lv2_meta_all = NULL;
 
 static void
diff --git a/ext/lv2/gstlv2.h b/ext/lv2/gstlv2.h
index 177f9b2c1..9f7258229 100644
--- a/ext/lv2/gstlv2.h
+++ b/ext/lv2/gstlv2.h
@@ -28,40 +28,40 @@
 
 #include "gstlv2utils.h"
 
-LilvWorld *world;
-LilvNode *atom_class;
-LilvNode *audio_class;
-LilvNode *control_class;
-LilvNode *cv_class;
-LilvNode *event_class;
-LilvNode *input_class;
-LilvNode *output_class;
-LilvNode *preset_class;
-LilvNode *state_iface;
-LilvNode *state_uri;
+extern LilvWorld *world;
+extern LilvNode *atom_class;
+extern LilvNode *audio_class;
+extern LilvNode *control_class;
+extern LilvNode *cv_class;
+extern LilvNode *event_class;
+extern LilvNode *input_class;
+extern LilvNode *output_class;
+extern LilvNode *preset_class;
+extern LilvNode *state_iface;
+extern LilvNode *state_uri;
 
-LilvNode *integer_prop;
-LilvNode *toggled_prop;
-LilvNode *designation_pred;
-LilvNode *in_place_broken_pred;
-LilvNode *optional_pred;
-LilvNode *group_pred;
-LilvNode *supports_event_pred;
-LilvNode *label_pred;
+extern LilvNode *integer_prop;
+extern LilvNode *toggled_prop;
+extern LilvNode *designation_pred;
+extern LilvNode *in_place_broken_pred;
+extern LilvNode *optional_pred;
+extern LilvNode *group_pred;
+extern LilvNode *supports_event_pred;
+extern LilvNode *label_pred;
 
-LilvNode *center_role;
-LilvNode *left_role;
-LilvNode *right_role;
-LilvNode *rear_center_role;
-LilvNode *rear_left_role;
-LilvNode *rear_right_role;
-LilvNode *lfe_role;
-LilvNode *center_left_role;
-LilvNode *center_right_role;
-LilvNode *side_left_role;
-LilvNode *side_right_role;
+extern LilvNode *center_role;
+extern LilvNode *left_role;
+extern LilvNode *right_role;
+extern LilvNode *rear_center_role;
+extern LilvNode *rear_left_role;
+extern LilvNode *rear_right_role;
+extern LilvNode *lfe_role;
+extern LilvNode *center_left_role;
+extern LilvNode *center_right_role;
+extern LilvNode *side_left_role;
+extern LilvNode *side_right_role;
 
-GstStructure *lv2_meta_all;
+extern GstStructure *lv2_meta_all;
 
 void gst_lv2_filter_register_element (GstPlugin *plugin,
                                       GstStructure * lv2_meta);