RFR: 8318696: Do not use LFS64 symbols on Linux [v4]

[Sam James]

> The LFS64 symbols provided by glibc are not part of any standard and were gated behind -D_LARGEFILE64_SOURCE in musl 1.2.4 (to be removed in 1.2.5). This commit replaces the usage of LFS64 symbols with their regular counterparts and defines -D_FILE_OFFSET_BITS=64, ensuring that functions will always act as their -64 variants on glibc.

Sam James has updated the pull request incrementally with two additional commits since the last revision:

 - sendfile64 -> sendfile
   
   Signed-off-by: Sam James <sam at gentoo.org>
 - buf64->buf
   
   Signed-off-by: Sam James <sam at gentoo.org>

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/16329/files
  - new: https://git.openjdk.org/jdk/pull/16329/files/e02b0715..5a66616f

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=16329&range=03
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=16329&range=02-03

  Stats: 4 lines in 1 file changed: 0 ins; 0 del; 4 mod
  Patch: https://git.openjdk.org/jdk/pull/16329.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/16329/head:pull/16329

PR: https://git.openjdk.org/jdk/pull/16329