Workaround for a behaviour change (bug?) in cmake 3.18
Workaround for a behaviour change (bug?) in cmake 3.18

.c files are no longer forced to be compiled as C in the
Visual Studio generator, and Visual Studio seems to
"autodetect" some .c files as C++, which causes all sorts
of problems in the sokol-samples.

.c files are now 'manually' to C mode.

floooh/fips,floooh/fips,floooh/fips