RFR: 8329546: Assume sized integral types are available

[Kim Barrett]

Please review this change that cleans up the inclusion of <stdint.h> and
<inttypes.h> when using gcc/clang as the compiler.

Testing: mach5 tier1

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

Commit messages:
 - include std headers unconditionally and cleanup

Changes: https://git.openjdk.org/jdk/pull/18586/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=18586&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8329546
  Stats: 26 lines in 1 file changed: 2 ins; 23 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/18586.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/18586/head:pull/18586

PR: https://git.openjdk.org/jdk/pull/18586