Prebuild command not execuded before cmake compiler check.

[Chuvi-w]

I've tryed to use this toolchain with stm32duino.

I received an error, looking like this:

/sketch/build_opt.h: No such file or directory

File build_opt.h should be created here

Script prebuild.sh should be executed from here. Note, that there is variant for Windows.

I've found no recipe.hooks.prebuild variant in ArduinoIDE Platform Specification, but in ArduinoIDE it works normally

[Chuvi-w]

Fixed in #44
Thanks to @gibwar