Fix 32bit overflow

Author: pghysels

src/sparse/fronts/FrontBLR.cpp

@@ -409,7 +409,7 @@ namespace strumpack {
             A.extract_front
               (F11, F12, F21, sep_begin_, sep_end_, this->upd_, task_depth);
             if (dupd) {
-              CBstorage_ = workspace.get(dupd*dupd);
+              CBstorage_ = workspace.get(std::size_t(dupd)*dupd);
               F22_ = DenseMW_t(dupd, dupd, CBstorage_.data(), dupd);
               F22_.zero();
             }

src/sparse/fronts/FrontDense.cpp

@@ -237,12 +237,7 @@ namespace strumpack {
       (F11_, F12_, F21_, this->sep_begin_, this->sep_end_,
        this->upd_, task_depth);
     if (dupd) {
-      CBstorage_ = workspace.get();
-      integer_t old_size = CBstorage_.size();
-      if (dupd*dupd > old_size) {
-        STRUMPACK_ADD_MEMORY((dupd*dupd - old_size)*sizeof(scalar_t));
-      }
-      CBstorage_.resize(dupd*dupd);
+      CBstorage_ = workspace.get(std::size_t(dupd)*dupd);
       F22_ = DenseMW_t(dupd, dupd, CBstorage_.data(), dupd);
       F22_.zero();
     }