Don't store a full 4-kB page in .data for only 11 bytes total

--- ./cmds/filesystem.c.bad	2023-03-25 19:41:39.000000000 +0100
+++ ./cmds/filesystem.c	2023-04-24 16:20:51.276359505 +0200
@@ -1463,25 +1463,16 @@
 static int write_swap_signature(int fd, u32 page_count, const uuid_t uuid)
 {
 	int ret;
-	static unsigned char swap[SZ_4K] = {
-		[0x400] = 0x01,
-		/* 0x404 .. 0x407 number of pages (little-endian) */
-		/* 0x408 .. 0x40b number of bad pages (unused) */
-		/* 0x40c .. 0x42b UUID */
-		/* Last bytes of the page */
-		[0xff6] = 'S',
-		[0xff7] = 'W',
-		[0xff8] = 'A',
-		[0xff9] = 'P',
-		[0xffa] = 'S',
-		[0xffb] = 'P',
-		[0xffc] = 'A',
-		[0xffd] = 'C',
-		[0xffe] = 'E',
-		[0xfff] = '2',
-	};
+	static unsigned char swap[SZ_4K];
 	u32 *pages = (u32 *)&swap[0x404];
 
+	swap[0x400] = 0x01;
+	/* 0x404 .. 0x407 number of pages (little-endian) */
+	/* 0x408 .. 0x40b number of bad pages (unused) */
+	/* 0x40c .. 0x42b UUID */
+	/* Last bytes of the page */
+	memcpy(&swap[0xff6], "SWAPSPACE2", 10);
+
 	*pages = cpu_to_le32(page_count);
 	memcpy(&swap[0x40c], uuid, 16);
 	ret = pwrite(fd, swap, SZ_4K, 0);