[refactor] remove gratuitous forward references in lifetime.d

[rainers]

this revealed a bad call to onFinalizeError.

I verified that the extra wrapper call is removed with -inline -O.

[rainers]

Another reason to do this PR is to use the common core.memory.GC interface instead of gc_* calls.

[andralex]

Noice. Do those replacement of gc_xxx calls with GC.xxx calls affect speed?

[rainers]

I checked the assembly output of lifetime.d compiled with -O -inline on Win32/Win64: there were no references to core.memory.GC in there, all the functions seemed to be inlined.

[andralex]

looking at assembly == guaranteed merge :)

[rainers]

Thanks.

Unfortunately, this has removed onOutOfMemoryError calls due to https://d.puremagic.com/issues/show_bug.cgi?id=11461 as the workaround is not added to the declaration in core.exception.

The fix is also found as part of #751, but
there is an alternative workaround suggested in the bug report which doesn't remove the "pure" attribute and seems better.

[rainers]

I created #753 to fix it.