move system include files to subdir

include/stdio.h

@@ -0,0 +1 @@
+extern int printf(char *, ...);

main.leg

@@ -1,6 +1,6 @@
 # main.leg -- C parser + interpreter
 #
-# Last edited: 2025-01-24 22:12:50 by piumarta on zora
+# Last edited: 2025-01-25 08:53:25 by piumarta on m1mbp
 
 %{
 ;
@@ -1339,7 +1339,9 @@ void popInput(void)
 
 FILE *sysOpen(char *path)
 {
-    FILE *fp = fopen(path, "r");
+    char abspath[1024];
+    snprintf(abspath, sizeof(abspath), "include/%s", path);
+    FILE *fp = fopen(abspath, "r");
     if (!fp) fatal("#include <%s>: %s", path, strerror(errno));
     return fp;
 }