toolchain/58663: gpt(1) biosboot.c doesn't compile on modern Linux

Kia ora koutou,
While looking at JBG's problems uncovered by GCC 14 I found a tools
portability bug in gpt(1) biosboot.c and filed the above PR for it.

The fix is super trivial, but since I'm a newly minted NetBSD developer
I'm supposed to get source changes reviews. If someone gives the PR an
okey-dokey, I'll get on with committing the following patch to CVS.

The problem is that daddr_t and off_t are 32 bits and 64 bits in size
respectively on Linux and then pointers get screwy.

diff -r 3a2c38eb3772 sbin/gpt/biosboot.c
--- a/sbin/gpt/biosboot.c       Tue Sep 03 19:51:02 2024 +0000
+++ b/sbin/gpt/biosboot.c       Wed Sep 04 15:08:01 2024 +1200
@@ -267,7 +267,7 @@
 #endif
        int ch;
        gpt_t ngpt = gpt;
-       daddr_t start = 0;
+       off_t start = 0;        /* off_t because of gpt_human_get() */
        uint64_t size = 0;
        int active = 0;
        unsigned int entry = 0;

Ngā mihi,
Lloyd