Merge pull request #3564 from RosettaCommons/vmullig/fix_signed_char_issue
Fixing an issue with assignment of -1 to a char
According to the C++ standard, the `char` type can be signed or unsigned -- it's up to the implementation. We have a spot in the Rosetta code where -1 is assigned to a `char`, and although that's fine for compilation on most systems, it breaks the Blue Gene/Q build. (It also likely breaks Android builds -- they also tend to default to `char == unsigned char`.) The simple fix is to declare this `char` to be `signed` explicitly.
In general, if you assign numeric values to a `char` or do math other than just incrementing or decrementing, it's a good idea to make it explicit whether you're working with a signed or unsigned `char`.