RFR: 8299915: Remove ArrayAllocatorMallocLimit and associated code

[Justin King]

Remove abstraction that is a holdover from Solaris. Direct usages of `MmapArrayAllocator` have been switched to normal `malloc`. The justification is that none of the code paths are called from signal handlers, so using `mmap` directly does not make sense and is potentially slower than going through `malloc` which can potentially re-use memory without making any system calls. The remaining usages of `ArrayAllocator` and `MallocArrayAllocator` are equivalent.

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Commit messages:
 - Use REALLOC_C_HEAP_ARRAY instead of NEW_C_HEAP_ARRAY/FREE_C_HEAP_ARRAY
 - Remove ArrayAllocatorMallocLimit

Changes: https://git.openjdk.org/jdk/pull/11931/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=11931&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8299915
  Stats: 336 lines in 13 files changed: 13 ins; 308 del; 15 mod
  Patch: https://git.openjdk.org/jdk/pull/11931.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/11931/head:pull/11931

PR: https://git.openjdk.org/jdk/pull/11931