[libcxx][test] Fix a test for the range of file offsets on ARMv7 Linux targets. (#123449)

Mark the `offset_range` test as UNSUPPORTED for the
`armv7-unknown-linux-gnueabihf` target (32-bit).

Ref PR #122798

Author: vvereschaka

libcxx/test/std/input.output/file.streams/fstreams/ifstream.members/offset_range.pass.cpp

@@ -28,6 +28,11 @@
 //
 // XFAIL: target=powerpc-{{.+}}-aix{{.*}}
 
+// By default, off_t is typically a 32-bit integer on ARMv7 Linux systems,
+// meaning it can represent file sizes up to 2GB (2^31 bytes) only.
+//
+// UNSUPPORTED: target=armv7-unknown-linux-gnueabihf
+
 #include <fstream>
 #include <iostream>
 #include <cassert>