Rename primary_thread to main_thread

This avoids the confusion of using two different phrases "main thread"
and "primary thread" internally to mean the same thing.  See:
http://lists.gnu.org/archive/html/emacs-devel/2016-12/msg01142.html
* src/thread.c (main_thread): Rename from primary_thread,
since the new name no longer clashes with main_thread_id
and Emacs internals normally call this the "main thread".
(init_main_thread): Rename from init_primary_thread.
(main_thread_p): Rename from primary_thread_p.
All uses changed.

1 files changed, 2 insertions, 2 deletions

diff --git a/src/alloc.c b/src/alloc.c
index 121d7042353..d74c4bec7e2 100644
--- a/src/alloc.c
+++ b/src/alloc.c
@@ -6404,7 +6404,7 @@ mark_object (Lisp_Object arg)
 
 #ifdef GC_CHECK_MARKED_OBJECTS
         m = mem_find (po);
-        if (m == MEM_NIL && !SUBRP (obj) && !primary_thread_p (po))
+        if (m == MEM_NIL && !SUBRP (obj) && !main_thread_p (po))
           emacs_abort ();
 #endif /* GC_CHECK_MARKED_OBJECTS */
 
@@ -6416,7 +6416,7 @@ mark_object (Lisp_Object arg)
 
         if (pvectype != PVEC_SUBR
             && pvectype != PVEC_BUFFER
-            && !primary_thread_p (po))
+            && !main_thread_p (po))
           CHECK_LIVE (live_vector_p);
 
         switch (pvectype)