RFR: 8296157: Rename FileMapInfo::space_at() to region_at() [v3]

[Matias Saavedra Silva]

> Most of the CDS code refers to a memory blocks inside a CDS file as "regions", represented by the type FileMapRegion. The method FileRegion* space_at() has been renamed to region_at() and all instances of its use have been replaced. Verified with tier 1-4 tests.

Matias Saavedra Silva has updated the pull request incrementally with one additional commit since the last revision:

  Fixed code alignment

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Changes:
  - all: https://git.openjdk.org/jdk/pull/10937/files
  - new: https://git.openjdk.org/jdk/pull/10937/files/f4aafa66..272861ed

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=10937&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=10937&range=01-02

  Stats: 5 lines in 3 files changed: 0 ins; 0 del; 5 mod
  Patch: https://git.openjdk.org/jdk/pull/10937.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/10937/head:pull/10937

PR: https://git.openjdk.org/jdk/pull/10937