udmabuf.c:30:17: warning: implicit declaration of function 'open'

[Naresh Kamboju <naresh.kamboju@xxxxxxxxxx>]

Following build warnings noticed while building stable-rc Linux 5.14.1-rc1
with gcc-11 for arm64 architecture.

aarch64-linux-gnu-gcc -I../../../../../usr/include/    udmabuf.c  -o
kselftest/drivers/dma-buf/udmabuf
udmabuf.c: In function 'main':
udmabuf.c:30:17: warning: implicit declaration of function 'open'; did
you mean 'popen'? [-Wimplicit-function-declaration]
   30 |         devfd = open(/dev/udmabuf, O_RDWR);
      |                 ^~~~
      |                 popen
udmabuf.c:42:15: warning: implicit declaration of function 'fcntl'
[-Wimplicit-function-declaration]
   42 |         ret = fcntl(memfd, F_ADD_SEALS, F_SEAL_SHRINK);
      |               ^~~~~
make[3]: Leaving directory
'/builds/linux/tools/testing/selftests/drivers/dma-buf'

Build config:
https://builds.tuxbuild.com/1xXcUtI2INra8KaHjOXXQMOyAD0/config

Reported-by: Linux Kernel Functional Testing <lkft@xxxxxxxxxx>

meta data:
-----------
    git_describe: v5.14-rc6-389-g95dc72bb9c03,
    git_repo: https://gitlab.com/Linaro/lkft/mirrors/stable/linux-stable-rc,
    git_sha: 95dc72bb9c032093e79e628a98c927b3db73a6c3,
    git_short_log: 95dc72bb9c03 (\Linux 5.14.1-rc1\),
    kconfig: [
        defconfig,
        https://raw.githubusercontent.com/Linaro/meta-lkft/sumo/recipes-kernel/linux/files/lkft.config,
        https://raw.githubusercontent.com/Linaro/meta-lkft/sumo/recipes-kernel/linux/files/lkft-crypto.config,
        https://raw.githubusercontent.com/Linaro/meta-lkft/sumo/recipes-kernel/linux/files/distro-overrides.config,
        https://raw.githubusercontent.com/Linaro/meta-lkft/sumo/recipes-kernel/linux/files/systemd.config,
        https://raw.githubusercontent.com/Linaro/meta-lkft/sumo/recipes-kernel/linux/files/virtio.config,
        CONFIG_ARM64_MODULE_PLTS=y
    ],
    kernel_version: 5.14.1-rc1,
    target_arch: arm64,
    targets: [
        dtbs,
        dtbs-legacy,
        headers,
        kernel,
        kselftest,
        kselftest-merge,
        modules
    ],
    toolchain: gcc-11,

steps to reproduce:
https://builds.tuxbuild.com/1xXcUtI2INra8KaHjOXXQMOyAD0/tuxmake_reproducer.sh

--
Linaro LKFT
https://lkft.linaro.org