First merge of 2.054 beta.

This corresponds to DMD commit a913ce4bc59a94a022a27e390fc841f4aededffb.

Doesn't build Phobos yet.
Handle "initializer outlining" for loop rewrites in 2.064.
Remove assertion triggered due to qualifier mismatch.
Do not leave __xopEquals for structs undefined.
Fix IRLandingPadCatchInfo initialization order warning.
Fix catch clause codegen.

In the 2.064 frontend, the catch variables have a zero
initializer, so DtoDeclarationExp overwrote the actually
caught exception with null.
Adjust _d_assert_msg return type.
Implement new ModuleInfo discovery/druntime startup scheme on Linux.

This is the same implementation that is used for DMD and
supports shared libraries (not yet tested).