-defaultlib flags

[Martin Nowak via digitalmars-d-ldc]

On 03/23/2016 11:02 PM, David Nadlinger via digitalmars-d-ldc wrote:
> 
> The difference is that DMD parses any `-l` arguments and ignores `lib`
> prefixes, `.so` suffixes and on `.a` suffixes passes `-Bstatic` to the
> linker before the respective `-l` argument.

Actually we were using -l:libphobos2.a and -l:libphobos2.so before, but
this didn't work w/ older ld versions, so I implemented this in the
linker code.
https://github.com/D-Programming-Language/dmd/pull/4975/commits/94c66eaa298c23c730df1de075efb8e6210c693f