This reverts commit 67c72f08.

While the linker produced import libraries might work with MSVC in
simple test cases, they don't if e.g. linking to multiple GNU ld
produced import libraries at the same time. (They end up importing
functions from the wrong libraries.) The ones produced by dlltool
work fine though.

This issue was pointed out by Hendrik Leppkes.
Signed-off-by: Martin Storsjö <martin@martin.st>