Add module declaration to ldc/arrayinit.d.
Cherry-picked merge of D-Programming-Language/druntime#858 from 2.066:

test/*/Makefile: Do not assume that $(ROOT) is a relative path.
Cherry-picked merge of D-Programming-Language/druntime#857 from 2.066:

[trivial] Make rt.minfo import in object_.d function-local.

The 2.065 frontend trips over this when building the druntime
tests in shared library mode with LDC (forward reference to the
Object base class of TypeInfo when accessing the latter from
within rt.util.container). No idea why this happens, or why it
doesn't with DMD, but this fixes it and it also is a small
improvement on its own regardless.
Backported D-Programming-Language/druntime#791 from 2.066:
fix for Issue 11543 - multiple definition of std.regex with shared library

The copy relocations for the ModuleInfo symbols generated
by the linker when building the main executable without PIC
enabled were throwing the module collision detection off.
Work around TLS address caching issue with multiplexing fibers across threads.

See: GitHub #666.
Cherry-picked merge of D-Programming-Language/druntime#718 from 2.066:
Fix for issue 11981 - deadlock during thread initialization on Posix
Revert "Work around TLS address caching issue with multiplexing fibers across threads."

This is no longer necessary, as D-Programming-Language/druntime#791
switched Thread.getThis() to use explicit pthreads TLS for a
completely unrelated reason anyway.

This reverts commit db7f8ee0295478e1bc67fcde1aa17e1616b6371c.
Cherry-picked D-Programming-Language/druntime#868 from 2.066:
Mark threadasm.S as not requiring an executable stack.