i18n: avoid parenthesized string as array initializer

i18n: avoid parenthesized string as array initializer

The syntax

    static const char ignore_error[] = ("something");

is invalid C.  A parenthesized string is not allowed as an array
initializer.

Some compilers, for example GCC and MSVC, allow this syntax as an
extension, but it is not a portable construct.  tcc does not parse it, for
example.

Remove the parenthesis from the definition of the N_() macro to
fix this.

Signed-off-by: Ramsay Jones <ramsay@ramsay1.demon.co.uk>
Acked-by: Jonathan Nieder <jrnieder@gmail.com>
Acked-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>