Forward declare strdup from <string.h> to avoid warning during compilation

Author: dns2utf8

src/grammar/parser-lalr-main.c

@@ -12,10 +12,13 @@
 #include <stdarg.h>
 #include <stdlib.h>
 #include <string.h>
+// Forward declare strdup from <string.h> to avoid warning during compilation
+char *strdup(const char *s);
 
 extern int yylex();
 extern int rsparse();
 
+
 #define PUSHBACK_LEN 4
 
 static char pushback[PUSHBACK_LEN];