Add fallback cli option

[kutu]

Currently const lv_font_t my_font is const, and fallback field can only be assigned by editing my_font.c directly.

after this line

lv_font_conv/lib/writers/lvgl/lv_table_head.js

Line 77 in 4955966

const lv_font_t ${f.font_name} = {

add

.fallback = &lv_font_montserrat_12,

where lv_font_montserrat_12 will be fallback cli option

[kisvegabor]

It's really useful. @puzrin?

[puzrin]

I dont' track current state of lvgl. Is .fallback something specific to new version?

[kutu]

https://docs.lvgl.io/8.3/overview/font.html#use-font-fallback
I started with lvgl8.3, so I don't know how old this option is

if I try to assign fallback option like in docs

my_font.fallback = &lv_font_montserrat_12;

I got error

Cannot assign to variable 'my_font' with const-qualified type 'const lv_font_t' (aka 'const struct _lv_font_t') ​clang(typecheck_assign_const)

[kisvegabor]

It was added in v8.2.