testing/ltp: fix the symbol redefinition link error

blacklist nftw64 to resolve symbol duplication errors,
the following are the detailed link error info:
```
/usr/bin/ld: /home/testing/vela/cmake_out/vela_vela/apps/testing/ltp/libapps_ltp_syscalls_nftw_nftw64.a(nftw64.c.o):(.bss.__odr_asan.next_fd+0x0): multiple definition of `__odr_asan.next_fd'; /home/testing/vela/cmake_out/vela_vela/apps/testing/ltp/libapps_ltp_syscalls_nftw_nftw.a(nftw.c.o):(.bss.__odr_asan.next_fd+0x0): first defined here
/usr/bin/ld: /home/testing/vela/cmake_out/vela_vela/apps/testing/ltp/libapps_ltp_syscalls_nftw_nftw64.a(nftw64.c.o):(.bss.__odr_asan.visit+0x0): multiple definition of `__odr_asan.visit'; /home/testing/vela/cmake_out/vela_vela/apps/testing/ltp/libapps_ltp_syscalls_nftw_nftw.a(nftw.c.o):(.bss.__odr_asan.visit+0x0): first defined here
/usr/bin/ld: /home/testing/vela/cmake_out/vela_vela/apps/testing/ltp/libapps_ltp_syscalls_nftw_nftw64.a(nftw64.c.o):(.bss.__odr_asan.dirlist+0x0): multiple definition of `__odr_asan.dirlist'; /home/testing/vela/cmake_out/vela_vela/apps/testing/ltp/libapps_ltp_syscalls_nftw_nftw.a(nftw.c.o):(.bss.__odr_asan.dirlist+0x0): first defined here
/usr/bin/ld: /home/testing/vela/cmake_out/vela_vela/apps/testing/ltp/libapps_ltp_syscalls_nftw_nftw64.a(nftw64.c.o):(.bss.__odr_asan.ebuf+0x0): multiple definition of `__odr_asan.ebuf'; /home/testing/vela/cmake_out/vela_vela/apps/testing/ltp/libapps_ltp_syscalls_nftw_nftw.a(nftw.c.o):(.bss.__odr_asan.ebuf+0x0): first defined here
/usr/bin/ld: /home/testing/vela/cmake_out/vela_vela/apps/testing/ltp/libapps_ltp_syscalls_nftw_nftw64.a(nftw64.c.o):(.bss.__odr_asan.s2+0x0): multiple definition of `__odr_asan.s2'; /home/testing/vela/cmake_out/vela_vela/apps/testing/ltp/libapps_ltp_syscalls_nftw_nftw.a(nftw.c.o):(.bss.__odr_asan.s2+0x0): first defined here
/usr/bin/ld: /home/testing/vela/cmake_out/vela_vela/apps/testing/ltp/libapps_ltp_syscalls_nftw_nftw64.a(nftw64.c.o):(.bss.__odr_asan.temp+0x0): multiple definition of `__odr_asan.temp'; /home/testing/vela/cmake_out/vela_vela/apps/testing/ltp/libapps_ltp_syscalls_nftw_nftw.a(nftw.c.o):(.bss.__odr_asan.temp+0x0): first defined here
```

Signed-off-by: guoshichao <guoshichao@xiaomi.com>

Author: extinguish

testing/ltp/CMakeLists.txt

@@ -581,7 +581,7 @@ if(CONFIG_TESTING_LTP)
       "open_kconfig"
       "close_kconfig"
       "firmware" # nuttx do not support linux firmware load framework
-    )
+      "nftw64")
 
     list(
       APPEND

testing/ltp/Makefile

@@ -470,6 +470,7 @@ BLACKWORDS += open_kconfig
 BLACKWORDS += close_kconfig
 
 BLACKWORDS += firmware # nuttx do not support linux firmware load framework
+BLACKWORDS += nftw64
 
 BLACKSRCS += $(TESTLINUX_DIR)/io/disktest/main.c
 BLACKSRCS += $(TESTLINUX_DIR)/io/direct_io/dma_thread_diotest.c