Bug 861: enable posix_memalign with PGI
Bug 857: workaround MSVC compilation issue.

--HG--
extra : source : c02cde4e91107b91c18bcaae1e5a959e63840c0e
In SparseQR, calling factorize() without analyzePattern() was broken.

--HG--
extra : source : 7b6329e8b6260f30ea398d8be1058508c70b25b9