unicode: optional table for better handling of neutral bidi chars

unicode: optional table for better handling of neutral bidi chars

Off:
function                                             old     new   delta
unicode_bidi_isrtl                                     -      55     +55
isrtl_str                                             51      65     +14
unicode_isrtl                                         55       -     -55
read_line_input                                     5003    4937     -66
------------------------------------------------------------------------------
(add/remove: 1/4 grow/shrink: 1/1 up/down: 69/-121)           Total: -52 bytes

On:
function                                             old     new   delta
static.neutral_b                                       -     320    +320
static.neutral_p                                       -     142    +142
unicode_bidi_isrtl                                     -      55     +55
unicode_bidi_is_neutral_wchar                          -      55     +55
isrtl_str                                             51      59      +8
unicode_isrtl                                         55       -     -55
read_line_input                                     5003    4937     -66
------------------------------------------------------------------------------
(add/remove: 4/4 grow/shrink: 1/1 up/down: 580/-121)          Total: 459 bytes

Signed-off-by: Tomas Heinrich <heinrich.tomas@gmail.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>