llvm-base's configure step produces inconsistent linker flags

[NathanHowell]

If the library search path and regular PATH variables point to different versions of LLVM the package configuration file will point to multiple versions of LLVM.

See http://projects.haskell.org/pipermail/haskell-llvm/2013-May/000327.html for details.

[amigalemming]

I think that llvm-base should exclusively ask 'llvm-config'. However I know there were issues with llvm-config mixing dynamic and static libraries in its answers. That's why configure.ac had code to filter some files out.

[Ralith]

A pure llvm-config approach has been implemented for Windows support in 1f9574d, and appears to function adequately. In light of that, I think we should revisit the decision to use autoconf on other platforms.

[amigalemming]

On Mon, 10 Jun 2013, Benjamin Saunders wrote:

A pure llvm-config approach has been implemented for Windows support,
and appears to function adequately.

How does it work?