bug#9990: valgrind warning in add_row_entry

[Dan Nicolaescu]

valgrind ./temacs -Q gets this warning:

==7487== Use of uninitialised value of size 8
==7487==    at 0x4140F4: update_window (dispnew.c:4212)
==7487==    by 0x414F32: update_window_tree (dispnew.c:3326)
==7487==    by 0x414F0E: update_window_tree (dispnew.c:3324)
==7487==    by 0x4181FD: update_frame (dispnew.c:3253)
==7487==    by 0x443EDB: redisplay_internal (xdisp.c:13175)
==7487==    by 0x4F6F47: read_char (keyboard.c:2443)
==7487==    by 0x4F9406: read_key_sequence.constprop.14 (keyboard.c:9290)
==7487==    by 0x4FB0D4: command_loop_1 (keyboard.c:1447)
==7487==    by 0x560015: internal_condition_case (eval.c:1499)
==7487==    by 0x4EE4AD: command_loop_2 (keyboard.c:1158)
==7487==    by 0x55FEF7: internal_catch (eval.c:1256)
==7487==    by 0x4EFA36: recursive_edit_1 (keyboard.c:1137)
==7487== 
==7487== 
==7487== ---- Attach to debugger ? --- [Return/N/n/Y/y/C/c] ---- Y

The line in question is:

4212      entry = row_table[i];


(gdb) p i
$1 = 0x157
(gdb) p row_table[i]
$2 = (struct row_entry *) 0x0
(gdb) p row_table_size
$3 = 0x193

Is it possible for the contents of row_table to be uninitialized?  Is this 
warning a false positive?