* config/tc-i386.c: Prototype many functions.

        (set_intel_syntax): Accept `prefix'/`noprefix' specifiers.
        (i386_immediate): Remove unused second argument.
        (i386_intel_operand): Fix i386_is_reg typo.
        (i386_operand): Use allow_naked_reg.
        (output_invalid): Make operand int for K&R.