add missing dependency on pkg-config

[dirk-thomas]

After being merged this patch needs to be cherry-picked into the ardent branch and a new patch release has to be made.

[wjwwood]

Lgtm, but please always describe why it is needed, explained by it or linking to failing jobs or something. Just declaring it needs to be done and leaving the rest up to the reviewer to figure out is not acceptable pr etiquette in my opinion.

[dirk-thomas]

Sure, the packages CMake extra file require pkg-config to be available (

resource_retriever/libcurl_vendor/libcurl_vendor-extras.cmake.in

Line 18 in 48193d3

message(FATAL_ERROR "Could not find pkg-config")

) but the manifest doesn't list it as a dependency.

[nuclearsandwich]

resource_retriever builds on top of this were failing. 🔴 Abin_uX64__resource_retriever.. #9 is an example. A snippet of the build log is below.

23:01:31 cmake: /opt/ros/ardent/opt/libcurl_vendor/lib/libcurl.so.4: no version information available (required by cmake)
23:01:31 -- The C compiler identification is GNU 5.4.0
23:01:31 -- The CXX compiler identification is GNU 5.4.0
23:01:31 -- Check for working C compiler: /usr/lib/ccache/x86_64-linux-gnu-gcc
23:01:31 -- Check for working C compiler: /usr/lib/ccache/x86_64-linux-gnu-gcc -- works
23:01:31 -- Detecting C compiler ABI info
23:01:31 -- Detecting C compiler ABI info - done
23:01:31 -- Detecting C compile features
23:01:31 -- Detecting C compile features - done
23:01:31 -- Check for working CXX compiler: /usr/lib/ccache/x86_64-linux-gnu-g++
23:01:31 -- Check for working CXX compiler: /usr/lib/ccache/x86_64-linux-gnu-g++ -- works
23:01:31 -- Detecting CXX compiler ABI info
23:01:31 -- Detecting CXX compiler ABI info - done
23:01:31 -- Detecting CXX compile features
23:01:31 -- Detecting CXX compile features - done
23:01:31 -- Found ament_cmake_ros: 0.4.0 (/opt/ros/ardent/share/ament_cmake_ros/cmake)
23:01:31 -- Found PythonInterp: /usr/bin/python3 (found suitable version "3.5.2", minimum required is "3") 
23:01:31 -- Using PYTHON_EXECUTABLE: /usr/bin/python3
23:01:31 -- Found ament_index_cpp: 0.4.0 (/opt/ros/ardent/share/ament_index_cpp/cmake)
23:01:31 -- Found libcurl_vendor: 2.0.1 (/opt/ros/ardent/share/libcurl_vendor/cmake)
23:01:31 -- Could NOT find PkgConfig (missing:  PKG_CONFIG_EXECUTABLE) 
23:01:31 CMake Error at /opt/ros/ardent/share/libcurl_vendor/cmake/libcurl_vendor-extras.cmake:18 (message):
23:01:31   Could not find pkg-config
23:01:31 Call Stack (most recent call first):
23:01:31   /opt/ros/ardent/share/libcurl_vendor/cmake/libcurl_vendorConfig.cmake:30 (include)
23:01:31   CMakeLists.txt:16 (find_package)