Fix lex source files so that they will be accepted by flex v2.6.3
PR 21059
binutils* config/bfin-lex.l: Support processing with flex 2.6.3.
* itbl-lex.l: Likewise.
gas * arlex.l: Support processing with flex 2.6.3.
* deflex.l: Likewise.
* syslex.l: Likewise.
ld * ldlex.l: Support processing with flex 2.6.3.