configure: Accept llvm-3.2

Previously the build system only checked for llvm-3.1 - 2.8.
Now also 3.2 and 3.2svn is accepted.

Signed-off-by: Fabian Deutsch <fabian.deutsch@gmx.de>
auto merge of #5561 : fabiand/rust/wllvm32, r=catamorphism

Previously the build system only checked for llvm-3.1 - 2.8.
Now also 3.2 and 3.2svn is accepted.

Signed-off-by: Fabian Deutsch <fabian.deutsch@gmx.de>