Remove ASM 2.0 dependency from AtAjLTWTests::testLTWUnweavable

Remove ASM 2.0 dependency from AtAjLTWTests::testLTWUnweavable

The test class UnweavableTest used ASM 2.0 API. I upgraded in two ways:
  1. Now the ASM 9.1 API is used. Probably works with much older
     versions too (just not as old as 2.0), as long as the method and
     constructor signatures are the same).
  2. The class now uses the AspectJ version of ASM (i.e. package names
     aj.org.objectweb.asm.*) and therefore can just use ASM as it is on
     the classpath for module 'tests' already. There is no more need to
     manually add '<pathelement path="${aj.root}/lib/asm/asm-2.0.jar"/>'
     to the Ant build script for that test.

Consequently, asm-2.0.jar can be eliminated from Git SCM completely,
because it was only used in this one test.

BTW, I also removed some deprecated API and other types of warnings in
UnweavableTest.

Signed-off-by: Alexander Kriegisch <Alexander@Kriegisch.name>