Hash :
acfac7ae
        
        Author :
  
        
        Date :
2022-12-01T18:39:52
        
      
Make dependency paths relocatable
The generated configurations for both CMake and pkg-config included
absolute paths to dependencies (OpenSSL, MbedTLS). This is contrary
to the general CMake advise to create relocatable packages [1].
Additionally, when building both mbedtls and libevent via CMake's
FetchContent in the same project, loading the project would fail with
  INTERFACE_INCLUDE_DIRECTORIES property contains path:
    "/home/user/project/cmake-build/_deps/mbedtls-build/include"
  which is prefixed in the source directory.
The required changes include:
- Adding the outer includes only to the BUILD_INTERFACE solves the
  makes the CMake paths relocatable and thus solves the FetchContent
  problem.
- Updates to libevent_*.pc.in fixes the relocatable issues for
  pkg-config and properly declares currently missing dependencies.
- Using components for linking to OpenSSL (requiring CMake 3.4)
  and MbedTLS. The new MbedTLS target names now match the component
  names of the MbedTLS' CMake project.
- Use the Threads CMake library reference instead of a direct
  reference to support both built-in pthread and -lpthread.
v2 (azat): get back CMAKE_REQUIRED_LIBRARIES
[1] https://cmake.org/cmake/help/v3.25/manual/cmake-packages.7.html#creating-relocatable-packages
      
#libevent pkg-config source file
prefix=@prefix@
exec_prefix=@exec_prefix@
libdir=@libdir@
includedir=@includedir@
Name: libevent_pthreads
Description: libevent_pthreads adds pthreads-based threading support to libevent
Version: @VERSION@
Requires: libevent_core
Libs: -L${libdir} -levent_pthreads@CMAKE_DEBUG_POSTFIX@
Libs.private: @CMAKE_THREAD_LIBS_INIT@ @LIBS@
Cflags: -I${includedir}