Compiler warnings about uninitialized variables

[davidcerny]

GCC 15 complains about the following instances of variables that may be used uninitialized:

ncl/ncl/nxsmultiformat.cpp

Line 455 in 7a110a5

unsigned currentTaxon;

ncl/ncl/nxsmultiformat.cpp

Line 554 in 7a110a5

unsigned currentTaxon;

ncl/ncl/nxscxxdiscretematrix.cpp

Line 167 in 7a110a5

NxsCharacterPattern patternTemp;

The first two of these are instances of the same pattern: the index variable of a for loop is declared outside of that loop's initialization section, so that its value remains accessible once the loop has executed. The third case looks a little more involved.