[rust][tools] Fix Rust build example configuration handling #4112

Job	Run time
A9 :default.cfg	1m 37s
A9 :kernel/kernel_basic.cfg	6m 45s
A9-smp :default.cfg	1m 45s
A9-rtsmart :default.cfg	1m 28s
RISCV-rtsmart :default.cfg	1m 12s
A9-rtsmart :kernel/kernel_basic.cfg	6m 30s
RISCV-smp :default.cfg	1m 45s
AARCH64 :default.cfg	1m 37s
AARCH64 :default.cfg	1m 21s
AARCH64-smp :default.cfg	1m 41s
AARCH64-rtsmart :default.cfg	1m 41s
XUANTIE-rtsmart :default.cfg	1m 56s
A9-smp :kernel/kernel_basic.cfg	7m 3s
A9-rtsmart :kernel/mem.cfg	1m 38s
A9-rtsmart :kernel/ipc.cfg	5m 46s
AARCH64-rtsmart :default.cfg	1m 20s
RISCV :kernel/kernel_basic.cfg	6m 44s
RISCV-rtsmart :kernel/mem.cfg	1m 12s
RISCV-rtsmart :kernel/ipc.cfg	5m 53s
RISCV :default.cfg	1m 17s
XUANTIE-rtsmart :kernel/mem.cfg	2m 0s
RISCV-rtsmart :kernel/kernel_basic.cfg	6m 36s
A9-smp :kernel/ipc.cfg	5m 45s
RISCV :kernel/atomic_c11.cfg	1m 18s
XUANTIE-rtsmart :kernel/kernel_basic.cfg	7m 39s
A9-smp :kernel/mem.cfg	1m 47s
A9 :kernel/mem.cfg	1m 37s
A9 :kernel/ipc.cfg	5m 25s
AARCH64 :kernel/mem.cfg	1m 30s
A9 :components/lwip.cfg	1m 39s
A9 :cpp11/cpp11.cfg	1m 25s
RISCV-smp :kernel/mem.cfg	1m 27s
A9 :kernel/atomic_c11.cfg	1m 27s
XUANTIE-rtsmart :kernel/ipc.cfg	6m 30s
RISCV :kernel/ipc.cfg	5m 18s
A9 :components/sal.cfg	1m 37s
AARCH64-rtsmart :kernel/mem.cfg	1m 31s
AARCH64-smp :default.cfg	1m 25s
RISCV :kernel/mem.cfg	1m 12s
A9 :components/netdev.cfg	1m 38s
AARCH64-smp :kernel/mem.cfg	1m 35s
A9 :components/dfs.cfg	1m 14s
	2h 1m 46s

Provide feedback