Add some variables to linker

[farbodpmz]

Hello
I am using esp32 with rust. I am going to use deftm library library.Sp I need to add these fields to linker in compile time.
EXTERN(_defmt_acquire);
EXTERN(_defmt_release);
EXTERN(__defmt_default_timestamp);
EXTERN(__DEFMT_MARKER_TIMESTAMP_WAS_DEFINED);
PROVIDE(_defmt_timestamp = __defmt_default_timestamp);
PROVIDE(_defmt_panic = __defmt_default_panic);

Any idea?