Issues with building RANBooster

[khooi8913]

Hi, when building RANBooster, we noticed two issues:

1. It seems that RANBooster (atleast how the Makefile/CMakeFiles are designed) assumes that DPDK should be installed system-wide, and
2. In the README, the PKG_CONFIG_PATH provided for building RANBooster seems to be problematic.

For (1), we tried installing DPDK to a custom directory to prevent intefering with our system-wide installation, but the compilation failed -- to get xRAN to point to our custom DPDK installation may required some non-trivial amount of work. So, we had to upgrade our system's DPDK version to get things moving. For now, we simply did the following to override our system's DPDK version:

cd RANBooster/dpdk-ranbooster/
sudo ninja -C build install

For (2), the current provided PKG_CONFIG_PATH is causing issues with during CMake, see the following log (truncated):

-- Configured legacy build target 'fhi_lib_make' (Makefile at /home/xzk/RANBooster/3p/phy/fhi_lib/lib).
-- Configuring done
CMake Error in src/dpdk/ru_sharing/CMakeLists.txt:
  Imported target "fhi_lib" includes non-existent path

    "/home/xzk/RANBooster/dpdk-ranbooster/build/kernel/linux"

  in its INTERFACE_INCLUDE_DIRECTORIES.  Possible reasons include:

  * The path was deleted, renamed, or moved to another location.

  * An install or uninstall procedure did not complete successfully.

  * The installation package was faulty and references files it does not
  provide.

To address the issue, the key changes to get the CMake working is to point PKG_CONFIG_PATH to the directory containing right the *.pc files:

# current
export PKG_CONFIG_PATH=$RANBOOSTER_SRC_PATH/dpdk-ranbooster/build/meson-uninstalled

# patched
export PKG_CONFIG_PATH=$RANBOOSTER_SRC_PATH/dpdk-ranbooster/build/meson-private