build: mkldnn compat: put symlinks together with generate lib

CMake allows overriding the place where the libraries are being
generated using:

``` cmake
set(CMAKE_ARCHIVE_OUTPUT_DIRECTORY some_place)
set(CMAKE_LIBRARY_OUTPUT_DIRECTORY some_place)
```

In this case, the `libdnnl.so` will be put in `some_place` instead of
usual `${CMAKE_CURRENT_BINARY_DIR}` location.

However, we generate the compat symlinks in the latter location. This
makes them point to non-existent library, which in turn:
1. Invalidates the symlink;
2. Betrays users expectations on find the library (which is though
   a symlink) in the proper location `some_place`.
3. Makes `make` regenerate the symlink all the time no matter whether
   it exists or not. That happens because `make` checks whether the
   target (symlink) is _older_ than the prerequisite (`libdnnl.so`).
   It seems that the date for symlink is checked by the date of the
   object it points to. Since the symlink points to nowhere, the
   target is considered always outdated.

This closes uxlfoundation#743.

common: nd_iterator: avoid idiv in a loop

build: bumped version to v0.21.5

fixup: fixup: benchdnn: eltwise: improve input data coverage

* 1) With fp16 argument, exp() is dispatched to fp16 version as well,
* overflows and produces inf instead of an fp32 value, resulting in
* 0 in the final answer, while it should be a non-zero value exceeding trh.
* 2) MSVC math functions are invariant to compiler options leaving the
* answer same no matter what. Current threshold is low for it. Slightly
* increasing it...

src: cpu: rnn: remove macro in omp simd loop

This is to workaround a compiler bug (affects icc19.1).

cpu: gemm: make sure to return out of memory if so

Some cases were still not returning proper status in case of out of
memory.

benchdnn: ip: add DLRM training sizes

build: bumped version to v1.2.2

scratchpad: work around corrupted unique_ptr usage

src: cpu: rnn: remove unused variables in jit_uni_gru_cell_postgemm_1

It caused "label is not found" error in Xbyak after enabling AutoGrow
mode by default in jit_generator