Replace backend$config by backend$inc_config

[myreen]

Currently, we have two compiler configs. The original one:

cakeml/compiler/backend/backendScript.sml

Lines 24 to 38 in 8f782f6

	Datatype:
	config =
	<| source_conf : source_to_flat$config
	; clos_conf : clos_to_bvl$config
	; bvl_conf : bvl_to_bvi$config
	; data_conf : data_to_word$config
	; word_to_word_conf : word_to_word$config
	; word_conf : word_to_stack$config
	; stack_conf : stack_to_lab$config
	; lab_conf : 'a lab_to_target$config
	; symbols : (mlstring # num # num) list
	; tap_conf : tap_config
	; exported : mlstring list (* field for Pancake entry points - empty for CakeML *)
	|>
	End

And the version adapted for Eval:

cakeml/compiler/backend/backendScript.sml

Lines 634 to 648 in 8f782f6

	Datatype:
	inc_config =
	<| inc_source_conf : source_to_flat$config
	; inc_clos_conf : clos_to_bvl$config
	; inc_bvl_conf : bvl_to_bvi$config
	; inc_data_conf : data_to_word$config
	; inc_word_to_word_conf : word_to_word$config
	; inc_word_conf : word_to_stack$config
	; inc_stack_conf : stack_to_lab$config
	; inc_lab_conf : lab_to_target$inc_config
	; inc_symbols : (mlstring # num # num) list
	; inc_tap_conf : tap_config
	; inc_exported : mlstring list
	|>
	End

The original is called config and the new version is called inc_config. The only difference between them is that inc_config drops asm_conf from within lab_conf, since it contains function fields in a record type. Function types don't serialise well to text (for Eval) and the cv translator also struggles them.

This issue is about replacing config by inc_config everywhere.