RFR: 8326406: Remove mapfile support from makefiles

[Magnus Ihse Bursie]

Once [JDK-8017234](https://bugs.openjdk.org/browse/JDK-8017234) is done, we have no need for mapfiles anymore in the JDK project. The mapfile handling was inherited from the old build system and is just messy. We should remove it to make the linking process more clear.

Note that this PR is [dependent on](https://mail.openjdk.org/pipermail/jdk-dev/2021-March/005232.html) https://github.com/openjdk/jdk/pull/17955.

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Depends on: https://git.openjdk.org/jdk/pull/17955

Commit messages:
 - 8326406: Remove mapfile support from makefiles

Changes: https://git.openjdk.org/jdk/pull/17982/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=17982&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8326406
  Stats: 54 lines in 4 files changed: 0 ins; 47 del; 7 mod
  Patch: https://git.openjdk.org/jdk/pull/17982.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/17982/head:pull/17982

PR: https://git.openjdk.org/jdk/pull/17982