Diet Build fails

[TechInterMezzo]

I get the following error under Windows 10 x64:

gumapiresolver.c.obj : error LNK2019: unresolved external symbol gum_module_api_resolver_new referenced in function gum_api_resolver_make
gumapiresolver.c.obj : error LNK2019: unresolved external symbol gum_swift_api_resolver_new referenced in function gum_api_resolver_make
gumbacktracer.c.obj : error LNK2019: unresolved external symbol gum_dbghelp_backtracer_new referenced in function gum_backtracer_make_accurate
gumbacktracer.c.obj : error LNK2019: unresolved external symbol gum_x86_backtracer_new referenced in function gum_backtracer_make_fuzzy

The problem seems to be the inconsistent use of #ifndef GUM_DIET.
For example the call of gum_x86_backtracer_new is not excluded in gumbacktracer.c but the whole implementation in gumx86backtracer.c is.