added pulp tests, added capability for pulp compilation

Created by: DavidM-EMUS

Added 18 tests for Xpulp instruction set. Two additional tests left out of this pull request due to test failures due to unknown causes. Of the 18 tests that were added, 3 fail due to issues in either rtl or the toolchain. Test pulp_vectorial_bit_manip fails due to toolchain issues with the pv.insert.(b/h) instructions. Test pulp_vectorial_add_sub fails due to toolchain issues with pv.add.(div2/div4/div8) and pv.sub.(div2/div4/div8). Test pulp_vectorial_complex fails due to rtl issue reported at https://github.com/openhwgroup/cv32e40p/issues/407.

These tests add limited coverage for all Xpulp instructions with the exception of hardware looping and post-increment load/store instructions (the two tests that were not added to this pull request).

The additions to cv32/sim/Common.mk change the compiler flags when compiling a custom test whose name starts with "pulp_". The new compiler flags allow for compilation with Xpulp enabled and should not effect the default compiler flags in any other circumstances.