Fix Issue 12427 - Building druntime with -debug=PRINTF fails.
Merge pull request #748 from AndrejMitrovic/Fix12427

Issue 12427 - Building druntime with -debug=PRINTF fails.
remove gratuitous forward references
this revealed a bad call to onFinalizeError
remove unused forward declarations to gc_*
Merge pull request #750 from rainers/cleanup_adi

remove unused forward declarations to gc_*
Merge pull request #749 from rainers/cleanup_lifetime

[refactor] remove gratuitous forward references in lifetime.d
avoid strict purity inference by passing void pointer
Merge pull request #753 from rainers/workaround_bug11461

Workaround 11461: avoid strong purity inference by passing null pointer to onOutOfMemoryError
epoll_event struct is packed
Merge pull request #754 from sumo/master

epoll_event struct is packed
Mark some functions in core.sys.posix.unistd as safe and nothrow
These functions should be trusted, not safe
Merge pull request #755 from tom-tan/safe-nothrow-core-sys-posix-unistd

Mark some functions in core.sys.posix.unistd as safe and nothrow