RFR: 8230043: Lazily load libverify

[Claes Redestad]

Hi,

please review this cleanup to untangle the old bytecode verifier
(libverify). It's currently linked and loaded eagerly and early during
bootstrap.

Webrev: http://cr.openjdk.java.net/~redestad/8230043/webrev.00/
Bug:    https://bugs.openjdk.java.net/browse/JDK-8230043

- removes dependency on libverify from libjava by moving the 
check_format.c functions into libjava (they don't need to be exported 
via JNI)
- fixed build to not link libjava with libverify
- removes the eager initialization of libverify in
os::native_java_library
- removes the verify_stubs and directs verifier.cpp to load and call 
VerifyClassForMajorVersion in libverify directly. The initialization
is synchronized on a new mutex, Verify_lock
- remove the unused VerifyClass entry point and simplify code in the
verifier by removing some indirections

Testing: tier1-4

Thanks!

/Claes