Some fixes for new PerThreadValue for clang and dune-gdt

- see https://gcc.gnu.org/gcc-6/porting_to.html#overloaded-abs

Rebase PerThreadValue on tbb::enumerable_thread_specific

The previous implemenation had the problem that tbb does not guarantee a fixed maximal number of threads even if it is set in task_scheduler_init.

Properly fix ambiguous operator* for FieldMatrix

This reverts commit 96aa32aa
because it broke gdt compile

This reverts commit c45193cf
because it broke gdt compile.

to facilitate debugging

[lapacke] add dorgqr, zungqr

[lpsolve] fix wrapper