At least during CppunitTest_sw_odfimport, Clang's
-fsanitize=implicit-signed-integer-truncation warns (for nB) that an "implicit
conversion from type 'long' of value -181 (64-bit, signed) to type 'const
sal_uInt16' (aka 'const unsigned short') changed the value to 65355 (16-bit,
unsigned)".

Change-Id: I91bd1413fca248f5f05331980d8ac92753d366ab
Reviewed-on: https://gerrit.libreoffice.org/68665
Tested-by: Jenkins
Reviewed-by: Stephan Bergmann <sbergman@redhat.com>