openbsd.stand: add patch to support 3x longer config lines (#381651)

pkgs/os-specific/bsd/openbsd/pkgs/cmd-buff-size.patch

@@ -0,0 +1,17 @@
+OpenBSD's bootloader supports input configuration lines from both the console
+and configuration files of only up to 133 characters. This is easy to break
+with nix store paths. Triple it to 399.
+
+diff --git a/sys/stand/boot/cmd.h b/sys/stand/boot/cmd.h
+index 5045f052b8b..9fc5ce9e50a 100644
+--- a/sys/stand/boot/cmd.h
++++ b/sys/stand/boot/cmd.h
+@@ -27,7 +27,7 @@
+  *
+  */
+ 
+-#define CMD_BUFF_SIZE		133
++#define CMD_BUFF_SIZE		399
+ #define BOOTDEVLEN		1024
+ 
+ struct cmd_table {

pkgs/os-specific/bsd/openbsd/pkgs/stand/package.nix

@@ -8,7 +8,10 @@ mkDerivation {
   path = "sys/arch/amd64/stand";
   extraPaths = [ "sys" ];
 
-  patches = [ ../sys/initpath.patch ];
+  patches = [
+    ../sys/initpath.patch
+    ./cmd-buff-size.patch
+  ];
 
   # gcc compat
   postPatch = ''