RFR: 8280901: MethodHandle::linkToNative stub is missing w/ -Xint

[Vladimir Ivanov]

MethodHandle::linkToNative linker doesn't have a dedicated stub for interpreter. A stub for compiled code is shared and it is invoked through i2c stub when accessed from interpreter. In interpreter-only mode, stubs for compiled code are not generated and linkToNative ends up in a broken state where `Method::_from_interpreted_entry` points to `i2c` stub while `Method::_from_compiled_entry` points to `c2i` stub.

Proposed fix unconditionally generates a stub for `MethodHandle::linkToNative` case irrespective whether it is a interpreter-only mode or not. 

Testing: test/jdk/java/foreign/ w/ -Xint

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Commit messages:
 - Fix

Changes: https://git.openjdk.java.net/jdk/pull/7459/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=7459&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8280901
  Stats: 2 lines in 1 file changed: 1 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/jdk/pull/7459.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/7459/head:pull/7459

PR: https://git.openjdk.java.net/jdk/pull/7459