Bug 857: workaround MSVC compilation issue.

--HG--
branch : 3.2
Bug 861: enable posix_memalign with PGI
(grafted from 2ef553b2f2b0e6d8e3e8d088c973034d068ba077)

--HG--
branch : 3.2
extra : source : 2ef553b2f2b0e6d8e3e8d088c973034d068ba077
merge

--HG--
branch : 3.2
In SparseQR, calling factorize() without analyzePattern() was broken.

--HG--
branch : 3.2