Bug 12151: Remove use of smartmatch operator in tools/batchMod.pl

Bug 12151: Remove use of smartmatch operator in tools/batchMod.pl

The '~~' smartmatch operator is used to compare MARC::Field->subfield(code)
(i.e. a string) and the text element of each MARC::Field->subfields() which
is also plain text.

Substituting '~~' for 'eq' should be harmless then.

Regards
To+

Sponsored-by: Universidad Nacional de Cordoba
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Katrin Fischer <Katrin.Fischer.83@web.de>
Passes QA script and tests.
Tested batch modification of items, no problems found.

Signed-off-by: Tomas Cohen Arazi <tomascohen@gmail.com>