x86: make offset_in_range()'s warning contents useful (again)

x86: make offset_in_range()'s warning contents useful (again)

In case there is something which gets shortened (perhaps only on a BFD64
build targeting a 32-bit binary), seeing the full original value is
often helpful to understand what's actually going wrong. Of course for
non-64-bit binaries we better wouldn't be seeing such warnings at all,
as they're often indicative of a behavioral difference between BFD64 and
!BFD64 builds.

Prior to "gas: drop sprint_value()", which introduced the use of
bfd_sprintf_vma(), the output had other shortcomings.