stm32CubeMX corrupts Makefile during re-write

When generating code on an existing Makefile project any existing C_DEFS are corrupted

C_DEFS = \
-DUSE_HAL_DRIVER \
-DSTM32F301x8 

becomes

-DC_DEFS = USE_HAL_DRIVER \
-DSTM32F301x8 

so the definition of C_DEFS is lost and random errors result from the dangling defines.

This is on version 5.6.1 but is has been an issue for a long time (at least a year).

I've also seen other strange behaviour on Makefile - like "# compile gcc flags" gets repeated every time the code is generated - one makefile now has the string 15 times on one line!!

Another is -isystem for system include file path, CubemX insists on prefixing it with -I so it fails with -Iisystem ....

I'll save all the other bugs I've found for another day! - the above are the most annoying!