RFR: 8340710: Optimize DirectClassBuilder::build

[Shaojin Wen]

Do some refactoring so that the code can be inlined by the C1/C2 optimizer.

1. DirectClassBuilder::build codeSize 361 -> 315
2. DirectCodeBuilder::writeExceptionHandlers codeSize 183 -> 31
3. BufWriterImpl::writeIndex codeSize 62 -> 37 (forceinline)
4. BufWriterImpl::writeU2 (forceinline)
5. Util::writeAttributes codSize 45 -> 40 (forceinline)
6. Util::writeList codSize 47 -> 42 (forceinline)

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Commit messages:
 - inline writeLong & local constantPool
 - fix write header
 - suggestion from @liach
 - force inline Util::writeAttributes & Util::writeList
 - force inline writeU2
 - force inline invalidIndex
 - optimize for writeExceptionHandlers for C1
 - optimize DirectClassBuilder::build

Changes: https://git.openjdk.org/jdk/pull/21118/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=21118&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8340710
  Stats: 50 lines in 4 files changed: 31 ins; 6 del; 13 mod
  Patch: https://git.openjdk.org/jdk/pull/21118.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/21118/head:pull/21118

PR: https://git.openjdk.org/jdk/pull/21118