Add check for large files in meson.build

A similar check existed in the MSVC scripts that have been removed in
v17 by 1301c80b21, but nothing of the kind was checked in meson when
building with a 4-byte off_t.

This commit adds a check to fail the builds when trying to use a
relation file size higher than 1GB when off_t is 4 bytes, like
./configure, rather than detecting these failures at runtime because the
code is not able to handle large files in this case.

Backpatch down to v16, where meson has been introduced.

Discussion: https://postgr.es/m/aQ0hG36IrkaSGfN8@paquier.xyz
Backpatch-through: 16

meson.build

@@ -451,6 +451,14 @@ else
   segsize = (get_option('segsize') * 1024 * 1024 * 1024) / blocksize
 endif
 
+# If we don't have largefile support, can't handle segment size >= 2GB.
+if cc.sizeof('off_t', args: test_c_args) < 8
+  segsize_bytes = segsize * blocksize
+  if segsize_bytes >= (2 * 1024 * 1024 * 1024)
+    error('Large file support is not enabled. Segment size cannot be larger than 1GB.')
+  endif
+endif
+
 cdata.set('BLCKSZ', blocksize, description:
 '''Size of a disk block --- this also limits the size of a tuple. You can set
    it bigger if you need bigger tuples (although TOAST should reduce the need