Static/dynamic library detection

[adrian-victor]

Cabal install does not report correctly the absence of the shared version of any extra-library. For example, when installing hmatrix, the configure process probes for the shared libraries for ATLAS and LAPACK and, failing to detect them, reports the absence of those packages, even if the static versions are present on the system. This is extremely confusing, as it suggests a system config issue, rather than a library type problem.