api: fix bug in function hdata_move when absolute value of count is greater than 1

(cherry picked from commit 9fe6ce1cdc9e66bfbc94fc2fd1b445fe07d75149)

ChangeLog.asciidoc

@@ -19,6 +19,8 @@ http://weechat.org/files/releasenotes/ReleaseNotes-devel.html[release notes]
 
 * core: fix modifier "weechat_print": discard only one line when several lines
   are displayed in same message (closes #171)
+* api: fix bug in function hdata_move when absolute value of count is greater
+  than 1
 * tests: fix build of tests when the build directory is outside source tree
   (closes #178)
 * tests: fix memory leak in tests launcher

src/core/wee-hdata.c

@@ -562,11 +562,11 @@ hdata_move (struct t_hdata *hdata, void *pointer, int count)
     for (i = 0; i < abs_count; i++)
     {
         pointer = hdata_pointer (hdata, pointer, ptr_var);
-        if (pointer)
-            return pointer;
+        if (!pointer)
+            break;
     }
 
-    return NULL;
+    return pointer;
 }
 
 /*