libdtrace: Stop relying on lex compatibility

It does not appear to be required, and as of commit 6b7e592c21
("lex: Do not let input() return 0 when end-of-file is reached") it
causes input to return 0 instead of EOF when end-of-input is reached.

PR:		253440
MFC after:	3 days
Sponsored by:	The FreeBSD Foundation

cddl/contrib/opensolaris/lib/libdtrace/common/dt_impl.h

@@ -717,7 +717,7 @@ extern dt_pcb_t *yypcb;		/* pointer to current parser control block */
 extern char yyintprefix;	/* int token prefix for macros (+/-) */
 extern char yyintsuffix[4];	/* int token suffix ([uUlL]*) */
 extern int yyintdecimal;	/* int token is decimal (1) or octal/hex (0) */
-extern char yytext[];		/* lex input buffer */
+extern char *yytext;		/* lex input buffer */
 extern int yylineno;		/* lex line number */
 extern int yydebug;		/* lex debugging */
 extern dt_node_t *yypragma;	/* lex token list for control lines */

cddl/lib/libdtrace/Makefile

@@ -129,8 +129,6 @@ SRCS+=		dis_tables.c
 DSRCS+=		regs_x86.d
 .endif
 
-LFLAGS+=-l
-
 YFLAGS+=-d
 
 LIBADD=	ctf elf proc pthread rtld_db