Add CV-X-IF extension to Spike. Improve diagnostics of extension loader.

Created by: PicoPET

File 'cva6/regress/spike/new-files/customext/cvxif_test.c' is a basic test program of the extension. Follow the instructions in lead comments to build and run the test, and to evaluate the outcome of the test.

Files affected:

• cva6/regress/install-spike.sh: Apply additional patches. Copy new files. Update copyright
• cva6/regress/spike-shared-fesvr-lib.patch: Update and move to separate Spike patch directory 'cva6/regress/spike/patches'.
• cva6/regress/spike/new-files/customext/cvxif.cc: New.
• cva6/regress/spike/new-files/customext/cvxif_test.c: Ditto.
• cva6/regress/spike/new-files/riscv/cvxif.h: Ditto.
• cva6/regress/spike/new-files/riscv/cvxif_base.cc: Ditto.
• cva6/regress/spike/patches/spike-cvxif-extension.patch: Ditto.
• cva6/regress/spike/patches/spike-dlopen-diagnostics.patch: Ditto.

Signed-off-by: Zbigniew Chamski zbigniew.chamski@thalesgroup.com