run: fix disabling the `c` extension #107

Job	Run time
generate-config	6s
build-spike / Build Spike	8s
generate-code (riscv_arithmetic_basic_test, uvm)	1h 2m 49s
generate-code (riscv_rand_instr_test, uvm)	1h 3m 13s
generate-code (riscv_jump_stress_test, uvm)	1h 2m 50s
generate-code (riscv_loop_test, uvm)	1h 3m 13s
generate-code (riscv_rand_jump_test, uvm)	1h 3m 11s
generate-code (riscv_mmu_stress_test, uvm)	1h 3m 16s
generate-code (riscv_no_fence_test, uvm)	1h 2m 52s
generate-code (riscv_illegal_instr_test, uvm)	1h 2m 48s
generate-code (riscv_ebreak_test, uvm)	1h 2m 53s
generate-code (riscv_ebreak_debug_mode_test, uvm)	1h 3m 17s
generate-code (riscv_full_interrupt_test, uvm)	1h 3m 11s
generate-code (riscv_unaligned_load_store_test, uvm)	1h 2m 56s
generate-code (riscv_non_compressed_instr_test, uvm)	1h 2m 54s
generate-code (riscv_hint_instr_test, uvm)	1h 3m 0s
generate-code (riscv_pmp_test, uvm)	1h 2m 49s
generate-code (riscv_arithmetic_basic_test, pyflow)	4m 21s
run-tests	0s
	15h 49m 47s

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