Fix CMakeLists.txt in libs/sockets to build on buster

[iliaplatone]

No description provided.

[pawel-soja]

Should I add Debian Buster to CI?

[iliaplatone]

I'm building on that, if you want yes.

[pawel-soja]

For the sake of readability of CMakeLists.txt,
I would very much like to skip the constant repetition of ${CMAKE_CURRENT_SOURCE_DIR}.

For Debian Buster, cmake is version 3.13 and ${CMAKE_CURRENT_SOURCE_DIR} can be omitted.
In the current pull request #1767 I'm working on, I introduced CI for the Debian Buster system and made additional fixes to make indiclientqt compile for the older version of Qt

@iliaplatone Could you please check if everything is ok?

[iliaplatone]

indi/libs/indibase/baseclient_p.h:6:10: fatal error: tcpsocket.h: No such file or directory
#include <tcpsocket.h>

[iliaplatone]

It needs that for the headers at least

[iliaplatone]

Oh.. some mess over there forgot to point to ${CMAKE_CURRENT_SOURCE_DIR}/ the include path

[pawel-soja]

Is the version change not enough?
I'm testing it on Debian Buster (docker):

cmake_minimum_required(VERSION 3.13)
project(sockets CXX)

find_package(Threads REQUIRED)
add_library(${PROJECT_NAME} STATIC "")

# Headers
list(APPEND ${PROJECT_NAME}_HEADERS
    tcpsocket.h
)

list(APPEND ${PROJECT_NAME}_PRIVATE_HEADERS
    tcpsocket_p.h
)

# Sources
list(APPEND ${PROJECT_NAME}_SOURCES
    tcpsocket.cpp
)

if(WIN32)
    list(APPEND ${PROJECT_NAME}_SOURCES
        tcpsocket_win.cpp
    )
else()
    list(APPEND ${PROJECT_NAME}_SOURCES
        tcpsocket_unix.cpp
    )
endif()

# Setup Target
target_sources(${PROJECT_NAME}
    PUBLIC
    ${${PROJECT_NAME}_SOURCES}
    ${${PROJECT_NAME}_HEADERS}
    PRIVATE
    ${${PROJECT_NAME}_PRIVATE_HEADERS}
)

target_include_directories(${PROJECT_NAME}
    PUBLIC ./
)

target_link_libraries(${PROJECT_NAME} Threads::Threads)

[iliaplatone]

Done, it builds here also.

[pawel-soja]

To confirm, it was enough to change the version only?

Do you want to merge this pull request as soon as possible?
Can you wait for the upcoming big changes (include Debian Buster) in https://github.com/indilib/indi/tree/refactor/cmake-drivers

[iliaplatone]

Yes that was enough. I can wait.