[Mangle] Add flag to asm labels to disable '\01' prefixing
[Mangle] Add flag to asm labels to disable '\01' prefixing

LLDB synthesizes decls using asm labels. These decls cannot have a mangle
different than the one specified in the label name. I.e., the '\01' prefix
should not be added.

Fixes an expression evaluation failure in lldb's TestVirtual.py on iOS.

rdar://45827323

Differential Revision: https://reviews.llvm.org/D67774

git-svn-id: 4c4cc70b1ef44ba2b7963015e681894188cea27e@372903 91177308-0d34-0410-b5e6-96231b3b80d8
(cherry picked from commit 6d75e80f0e67c33159c3ecc1dad40de61db9ee99)

apple/swift-lldb,apple/swift-lldb,apple/swift-lldb,apple/swift-lldb,apple/swift-lldb,apple/swift-lldb