RFR: 8287396 LIR_Opr::vreg_number() and data() can return negative number [v2]

[Dean Long]

> This PR does two things:
> - reverts the incorrect change to non_data_bits that included pointer_bits
> - treats the data() as an unsigned int to prevent a high bit being treated as a negative number

Dean Long has updated the pull request incrementally with one additional commit since the last revision:

  set vreg_max to a more reasonable limit (10000)

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Changes:
  - all: https://git.openjdk.java.net/jdk/pull/8912/files
  - new: https://git.openjdk.java.net/jdk/pull/8912/files/3bc73a2e..5e19c9f7

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=8912&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=8912&range=00-01

  Stats: 3 lines in 1 file changed: 2 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/jdk/pull/8912.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/8912/head:pull/8912

PR: https://git.openjdk.java.net/jdk/pull/8912