Changed the tryfinally handlers to a more generalized EnclosingHandler.
Changed ClassInfoS to be mutable so they can be used as locks.
Added new BB after throw ala return/break etc.
Fixed problems with label collisions when using labels inside inline asm. LabelStatement is now easily reached given its
Identifier, which should be useful elsewhere too.
Enabled inline asm for building the lib/compiler/llvmdc runtime code, fixing branches out of asm makes this possible.
Renamed emit_finallyblocks to DtoFinallyBlocks and moved to llvmhelpers.
Added enclosingtryfinally to AsmBlockStatement, so branches out of asm blocks respect finallys.
Refactored some GotoStatement code into DtoGoto.
