LLD already writes a build id if debug info is enabled.

Some projects set --pie-executable to avoid GNU ld bugs about stripping
base relocations from an executable when they actually are used.
Since -fixed:no is the default (and we don't support setting the
-fixed option via the MinGW frontend), we don't need to handle this.

--disable-auto-image-base is ignored just like --enable-auto-image-base
(as we ignore from before).

Differential Revision: https://reviews.llvm.org/D40031

llvm-svn: 318285