Convert lexer to talloc and add xtalloc wrappers.

The lexer was previously using strdup (expecting the parser to free),
but is now more consistent, easier to use, and slightly more efficent
by using talloc along with the parser.

Also, we add xtalloc and xtalloc_strdup wrappers around talloc and
talloc_strdup to put all of the out-of-memory-checking code in one
place.

glcpp.h

@@ -55,7 +55,7 @@ glcpp_parser_destroy (glcpp_parser_t *parser);
 /* Generated by glcpp-lex.l to glcpp-lex.c */
 
 int
-yylex_init (yyscan_t *scanner);
+yylex_init_extra (glcpp_parser_t *parser, yyscan_t* scanner);
 
 int
 yylex (yyscan_t scanner);
@@ -68,4 +68,14 @@ yylex_destroy (yyscan_t scanner);
 int
 yyparse (glcpp_parser_t *parser);
 
+/* xtalloc - wrappers around talloc to check for out-of-memory */
+
+#define xtalloc(ctx, type) (type *)xtalloc_named_const(ctx, sizeof(type), #type)
+
+void *
+xtalloc_named_const (const void *context, size_t size, const char *name);
+
+char *
+xtalloc_strdup (const void *t, const char *p);
+
 #endif