RFR: 8264149 BreakpointInfo::set allocates metaspace object in VM thread

[Coleen Phillimore]

This change creates a Metaspace::allocate function that doesn't pass TRAPS to be used by MethodCounters.  TRAPS and exceptions shouldn't be thrown from non-JavaThreads.

Tested with tier1-7.

-------------

Commit messages:
 - Merge branch 'master' into metaspace
 - Comment updates.
 - Add Metaspace::allocate for non-java threads that return null.
 - Add Metaspace::allocate for non-java threads that return null.

Changes: https://git.openjdk.java.net/jdk/pull/3207/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=3207&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8264149
  Stats: 89 lines in 10 files changed: 42 ins; 13 del; 34 mod
  Patch: https://git.openjdk.java.net/jdk/pull/3207.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/3207/head:pull/3207

PR: https://git.openjdk.java.net/jdk/pull/3207