SAVENEX: fix unstable BMP loader (undefined behaviour in source)
SAVENEX: fix unstable BMP loader (undefined behaviour in source)

In C++ if you write "fread(f,...) + fread(f,..)", the compiler can (and
will) pick any side to evaluate first, mixing the order how the data
from file are read.

z00m128/sjasmplus,z00m128/sjasmplus,z00m128/sjasmplus