genksyms: make source_file a local variable in lexer

This is only used in yylex() in lex.l
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

scripts/genksyms/genksyms.c

@@ -29,7 +29,7 @@ static struct symbol *symtab[HASH_BUCKETS];
 static FILE *debugfile;
 
 int cur_line = 1;
-char *cur_filename, *source_file;
+char *cur_filename;
 int in_source_file;
 
 static int flag_debug, flag_dump_defs, flag_reference, flag_dump_types,

scripts/genksyms/genksyms.h

@@ -47,7 +47,7 @@ typedef struct string_list **yystype;
 #define YYSTYPE yystype
 
 extern int cur_line;
-extern char *cur_filename, *source_file;
+extern char *cur_filename;
 extern int in_source_file;
 
 struct symbol *find_symbol(const char *name, enum symbol_type ns, int exact);

scripts/genksyms/lex.l

@@ -125,6 +125,7 @@ yylex(void)
 
   static int suppress_type_lookup, dont_want_brace_phrase;
   static struct string_list *next_node;
+  static char *source_file;
 
   int token, count = 0;
   struct string_list *cur_node;