At least during CppunitTest_sw_uwriter, some m_nStrResId is read so that Clang's
-fsanitize=implicit-signed-integer-truncation warned that an "implicit
conversion from type 'int' of value 74752 (32-bit, signed) to type 'sal_uInt16'
(aka 'unsigned short') changed the value to 9216 (16-bit, unsigned)".

Change-Id: I39f12d931bb18eea909494c8d7c9c0348fb71f27
Reviewed-on: https://gerrit.libreoffice.org/68664
Tested-by: Jenkins
Reviewed-by: Stephan Bergmann <sbergman@redhat.com>