Ninja support

[Risto97]

Its very close to have Ninja support for SoCMake, there are minor things that are making it fail now

1. Ninja does not like when a multiple targets generate the same outputs.
   For example here:
   

   SoCMake/cmake/sim/ghdl/ghdl.cmake

   Lines 210 to 217 in 308fc14

   	add_custom_command(
   	OUTPUT ${STAMP_FILE}
   	COMMAND ${ghdl_analyze_cmd}
   	COMMAND touch ${STAMP_FILE}
   	BYPRODUCTS ${cf_files} ${obj_files}
   	WORKING_DIRECTORY ${OUTDIR}
   	DEPENDS ${VHDL_SOURCES} ${__ghdl_subdep_stamp_files}
   	COMMENT ${DESCRIPTION}

BYPRODUCTS are used for cleaning the additional generated files, and one file repeats for multiple custom commands:

SoCMake/cmake/sim/ghdl/ghdl.cmake

Line 197 in 308fc14

list(APPEND cf_files "${lib_outdir}/${__comp_lib_name}-obj${STANDARD}.cf")

We should use ADDITIONAL_CLEAN_FILES property for this instead

---

Ninja comes with some nice features compared to Make.

• It can list the input file dependencies for a target with ninja -t inputs
• It can generate graph with file level dependencies (compared to CMake target level) with ninja -t graph
• It should be faster?
• Browse the dependencies in the web browser with ninja -t browse
• Possibly solves the file dependencies for custom command across subdirectories, so add_dependencies are not needed anymore
• Custom status messages with NINJA_STATUS variable
• And more

[Risto97]

@benoitdenkinger @mtravaillard
Could we add a CI step for gitlab to run all the tests with Ninja along with Make?
I will add it for github CI.

I am not sure if this issue is done or there are more tools to be converted