unwind: give all exported functions "unwind_" prefix

* unwind.c (init_unwind_addr_space): Rename to unwind_init.
(init_libunwind_ui): Rename to unwind_tcb_init.
(free_libunwind_ui): Rename to unwind_tcb_fin.
(delete_mmap_cache): Rename to unwind_cache_invalidate.
(print_stacktrace): Rename to unwind_print_stacktrace.
* defs.h: Update prototypes.
* mem.c: All callers updated.
* process.c: Likewise.
* strace.c: Likewise.
* syscall.c: Likewise.

Signed-off-by: Masatake YAMATO <yamato@redhat.com>
diff --git a/syscall.c b/syscall.c
index 50b41ba..4ed971f 100644
--- a/syscall.c
+++ b/syscall.c
@@ -2708,7 +2708,7 @@
 
 #ifdef USE_LIBUNWIND
 	if (stack_trace_enabled)
-		print_stacktrace(tcp);
+		unwind_print_stacktrace(tcp);
 #endif
 
  ret: