RFR: 8267265: Use new IR Test Framework to create tests for C2 Ideal transformations

[Cesar Soares]

Hi, can I please get some reviews for this Pull Request? Here is a summary of the changes:

- Add tests, using the new IR-based test framework, for several of the Ideal transformations on Add, Sub, Mul, Div, Loop nodes and some simple Scalar Replacement transformations.
- Add more default IR regex's to IR-based test framework.

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Commit messages:
 - Tests for some Ideal transformations

Changes: https://git.openjdk.java.net/jdk/pull/7434/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=7434&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8267265
  Stats: 1968 lines in 10 files changed: 1968 ins; 0 del; 0 mod
  Patch: https://git.openjdk.java.net/jdk/pull/7434.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/7434/head:pull/7434

PR: https://git.openjdk.java.net/jdk/pull/7434