tests for 'onehot';
tests for 'pmux2shiftx';
tests for 'wblif'.

Add tests for commits:
- Add "wreduce -keepdc";
- Add "fmcombine -initeq -anyeq";
- Add "stat -tech xilinx";
- Add "synth_xilinx -arch".

Testing problems:

1.scc_feedback - Feedback is detected not in each case(with different
options).
2.splice/splice_port - No any changes in the dump after splice -port
command.
3.test_cell/test_cell_macc - ERROR: Assert `port_declared == true'
failed in kernel/rtlil.cc:1352.

Revert "Fix tests in backends,regression for new Yosys revision; Add new tests to frontends,misc,regression;"

This reverts commit e9fb66a3.

This reverts commit c9a8d4a8.

Fix tests in backends,regression for new Yosys revision; Add new tests to frontends,misc,regression;

Add new tests to backends and architecture;
Merge commit "Add regression test for Yosys PR 896"

Testing problems:

1. "sat -tempinduct_def":
+#ERROR: Assert `!undef_mode || model_undef' failed in
./kernel/satgen.h:90.

2. "share -force":
+#ERROR: Abort in passes/opt/share.cc:724.