element: rename gst_element_message_new_details() to gst_make_element_message_details()

Fixes g-i warning "Gst: Constructor return type mismatch
symbol='gst_element_message_new_details' constructed='Gst.Element'
return='Gst.Structure'".

This is a newly-added function in git that has not been in a stable
release yet, so it's fine to rename it. It's also only used indirectly
via macros.

docs/gst/gstreamer-sections.txt

@@ -904,7 +904,7 @@ gst_element_change_state
 <SUBSECTION element-messages>
 gst_element_message_full
 gst_element_message_full_with_details
-gst_element_message_details_new
+gst_make_element_message_details
 gst_element_post_message
 
 <SUBSECTION element-query>

gst/gstelement.c

@@ -3479,7 +3479,7 @@ _priv_gst_element_cleanup (void)
 }
 
 GstStructure *
-gst_element_message_details_new (const char *name, ...)
+gst_make_element_message_details (const char *name, ...)
 {
   GstStructure *structure;
   va_list varargs;

gst/gstelement.h

@@ -399,8 +399,8 @@ typedef enum
  */
 #define GST_ELEMENT_START_TIME(elem)            (GST_ELEMENT_CAST(elem)->start_time)
 
-GstStructure *gst_element_message_details_new(const char *name, ...);
-#define GST_ELEMENT_MESSAGE_MAKE_DETAILS(args) gst_element_message_details_new args
+GstStructure *gst_make_element_message_details (const char *name, ...);
+#define GST_ELEMENT_MESSAGE_MAKE_DETAILS(args) gst_make_element_message_details args
 
 /**
  * GST_ELEMENT_ERROR_WITH_DETAILS:

win32/common/libgstreamer.def

@@ -540,7 +540,6 @@ EXPORTS
 	gst_element_link_pads_full
 	gst_element_lost_state
 	gst_element_make_from_uri
-	gst_element_message_details_new
 	gst_element_message_full
 	gst_element_message_full_with_details
 	gst_element_no_more_pads
@@ -690,6 +689,7 @@ EXPORTS
 	gst_library_error_get_type
 	gst_library_error_quark
 	gst_lock_flags_get_type
+	gst_make_element_message_details
 	gst_map_flags_get_type
 	gst_memory_alignment DATA
 	gst_memory_copy