Bug in Mxalloc() detection

[mikrosk]

cleancode/common/mxalloc.c

Line 33 in 9dd4e6f

atari_mxalloc_avail = ((Sversion()&0xFF)>=0x01) | (Sversion()>=0x1900);

contains quite a suspicious code:

• it checks for major GEMDOS version 1.x (is there such?)
• it uses | instead of || for the check but it works by chance because previous condition always (?) fails

[pmandin]

I don't know where the check for the lower byte comes from, maybe difference between MegaSTe and TT (both have 0.19) ?
I copy/pasted it from SDL, (so same problem there).

Anyway, fixed