scanner/parser. FreeBSD recently made 'flex' its default implementation
of 'lex'. One of the incompatibilities of 'flex' vs. 'lex' is that
if you longjmp() out of the scanner, you must call yyrestart()
before doing another scan (as documented in flex(1)). So add an
invocation to yyrestart() in lex_init(). This change should be
backwards compatible with the original 'lex'.
PR: bin/24116
