RFR: 8266498: Make debug ps() call print_stack

[Coleen Phillimore]

Fix ps() call print_stack.  Tested manually and with fastdebug and debug.  Also removed hsfind() because find() is the same thing and nobody's using dbx anymore (and the overload that made me add it might be long gone).
Tested with tier1 sanity.

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Commit messages:
 - 8266498: Make debug ps() call print_stack
 - 8266498: Make debug ps() call print_stack

Changes: https://git.openjdk.java.net/jdk/pull/3861/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=3861&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8266498
  Stats: 15 lines in 1 file changed: 0 ins; 12 del; 3 mod
  Patch: https://git.openjdk.java.net/jdk/pull/3861.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/3861/head:pull/3861

PR: https://git.openjdk.java.net/jdk/pull/3861