FindOpenSSL: use extra dependencies from pkg-config as well

This is important if OpenSSL is linked against an external zlib.

Modules/FindOpenSSL.cmake

@@ -112,11 +112,31 @@ The following variables may be set to control search behavior:
 #]=======================================================================]
 
 macro(_OpenSSL_test_and_find_dependencies ssl_library crypto_library)
+  unset(_OpenSSL_extra_static_deps)
   if((CMAKE_SYSTEM_NAME STREQUAL "Linux") AND
      (("${ssl_library}" MATCHES "\\${CMAKE_STATIC_LIBRARY_SUFFIX}$") OR
       ("${crypto_library}" MATCHES "\\${CMAKE_STATIC_LIBRARY_SUFFIX}$")))
     set(_OpenSSL_has_dependencies TRUE)
-    find_package(Threads)
+    unset(_OpenSSL_has_dependency_zlib)
+    if(_OPENSSL_LIBRARIES)
+      unset(_OpenSSL_has_dependency_dl)
+      foreach(_OPENSSL_DEP_LIB IN LISTS _OPENSSL_LIBRARIES)
+        if (_OPENSSL_DEP_LIB STREQUAL "ssl" OR _OPENSSL_DEP_LIB STREQUAL "crypto")
+          # ignoring: these are the targets
+        elseif(_OPENSSL_DEP_LIB STREQUAL CMAKE_DL_LIBS)
+          set(_OpenSSL_has_dependency_dl TRUE)
+        elseif(_OPENSSL_DEP_LIB STREQUAL "z")
+          find_package(ZLIB)
+          set(_OpenSSL_has_dependency_zlib TRUE)
+        else()
+          list(APPEND _OpenSSL_extra_static_deps "${_OPENSSL_DEP_LIB}")
+        endif()
+      endforeach()
+      unset(_OPENSSL_DEP_LIB)
+    else()
+      set(_OpenSSL_has_dependency_dl TRUE)
+      find_package(Threads)
+    endif()
   else()
     set(_OpenSSL_has_dependencies FALSE)
   endif()
@@ -126,14 +146,25 @@ function(_OpenSSL_add_dependencies libraries_var)
   if(CMAKE_THREAD_LIBS_INIT)
     list(APPEND ${libraries_var} ${CMAKE_THREAD_LIBS_INIT})
   endif()
-  list(APPEND ${libraries_var} ${CMAKE_DL_LIBS})
+  if(_OpenSSL_has_dependency_zlib)
+    list(APPEND ${libraries_var} ${ZLIB_LIBRARY})
+  endif()
+  if(_OpenSSL_has_dependency_dl)
+    list(APPEND ${libraries_var} ${CMAKE_DL_LIBS})
+  endif()
+  list(APPEND ${libraries_var} ${_OpenSSL_extra_static_deps})
   set(${libraries_var} ${${libraries_var}} PARENT_SCOPE)
 endfunction()
 
 function(_OpenSSL_target_add_dependencies target)
   if(_OpenSSL_has_dependencies)
-    set_property( TARGET ${target} APPEND PROPERTY INTERFACE_LINK_LIBRARIES Threads::Threads )
-    set_property( TARGET ${target} APPEND PROPERTY INTERFACE_LINK_LIBRARIES ${CMAKE_DL_LIBS} )
+    set_property( TARGET ${target} APPEND PROPERTY INTERFACE_LINK_LIBRARIES Threads::Threads ${_OpenSSL_extra_static_deps})
+    if(_OpenSSL_has_dependency_dl)
+      set_property( TARGET ${target} APPEND PROPERTY INTERFACE_LINK_LIBRARIES ${CMAKE_DL_LIBS} )
+    endif()
+    if(_OpenSSL_has_dependency_zlib)
+      set_property( TARGET ${target} APPEND PROPERTY INTERFACE_LINK_LIBRARIES ZLIB::ZLIB )
+    endif()
   endif()
   if(WIN32 AND OPENSSL_USE_STATIC_LIBS)
     if(WINCE)
@@ -719,3 +750,6 @@ endif()
 
 unset(_OPENSSL_FIND_PATH_SUFFIX)
 unset(_OPENSSL_NAME_POSTFIX)
+unset(_OpenSSL_extra_static_deps)
+unset(_OpenSSL_has_dependency_dl)
+unset(_OpenSSL_has_dependency_zlib)