Correct some error handling path in libc_emcc #4032

Job	Run time
build_llvm_libraries / build_llvm_libraries	3m 1s
build_llvm_libraries_xtensa / build_llvm_libraries	2m 59s
spec_test_on_qemu (boards/xtensa/esp32s3/esp32s3-devkit/configs/qemu_debug, xtensa, none, -t aot,...	12m 45s
spec_test_on_qemu (boards/arm/imx6/sabre-6quad/configs/nsh, thumbv7_vfp, dp, -t aot -X, CONFIG_IN...	11m 20s
spec_test_on_qemu (boards/arm/imx6/sabre-6quad/configs/nsh, thumbv7_vfp, dp, -t aot, CONFIG_INTER...	11m 26s
spec_test_on_qemu (boards/risc-v/qemu-rv/rv-virt/configs/nsh64, riscv64, none, -t aot, CONFIG_INT...	8m 51s
spec_test_on_qemu (boards/risc-v/qemu-rv/rv-virt/configs/nsh, riscv32, none, -t aot -X, CONFIG_IN...	8m 56s
spec_test_on_qemu (boards/xtensa/esp32s3/esp32s3-devkit/configs/qemu_debug, xtensa, none, -t aot ...	12m 43s
spec_test_on_qemu (boards/risc-v/qemu-rv/rv-virt/configs/nsh, riscv32, none, -t aot, CONFIG_INTER...	9m 0s
	1h 21m 1s

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