pptok.c: quick-and-dirty downcasing during prehashing
pptok.c: quick-and-dirty downcasing during prehashing

Speed up pptok.c by just doing |= 0x20 instead of calling tolower() for
every character during prehashing.  This is good enough for our needs,
since we don't have any tokens containing the characters @ [ \ ] _ nor
any high-bit characters (in which case we'd have to worry about multibyte
anyway.)

projedi/nasm,letolabs/nasm,letolabs/nasm,techkey/nasm,projedi/nasm,Distrotech/nasm,turingstudio/nasm,techkey/nasm,Distrotech/nasm,projedi/nasm,techkey/nasm,projedi/nasm,techkey/nasm,letolabs/nasm,turingstudio/nasm,Distrotech/nasm,turingstudio/nasm,turingstudio/nasm,Distrotech/nasm,projedi/nasm,techkey/nasm