core: fix uninitialized value in function string_decode_base64

ChangeLog

@@ -13,6 +13,7 @@ http://weechat.org/files/releasenotes/ReleaseNotes-devel.html[release notes]
 
 == Version 0.4.4 (under dev)
 
+* core: fix uninitialized value in function string_decode_base64
 * core: fix memory leak and use of invalid pointer in split of string (in case
   of insufficient memory)
 * core: fix potential NULL pointer in function gui_color_emphasize

src/core/wee-string.c

@@ -2425,6 +2425,10 @@ string_decode_base64 (const char *from, char *to)
     {
         length = 0;
         for (i = 0; i < 4; i++)
+        {
+            in[i] = 0;
+        }
+        for (i = 0; i < 4; i++)
         {
             c = 0;
             while (ptr_from[0] && (c == 0))