enhance json-c package finding

Author: qrkourier

library/CMakeLists.txt

@@ -47,7 +47,20 @@ if (ziti_DEVELOPER_MODE)
     endif ()
 endif ()
 
-find_package(json-c CONFIG REQUIRED)
+find_package(json-c CONFIG QUIET)
+if(NOT json-c_FOUND)
+    find_package(PkgConfig REQUIRED)
+    pkg_check_modules(JSONC REQUIRED json-c)
+    include_directories(${JSONC_INCLUDE_DIRS})
+    link_libraries(${JSONC_LIBRARIES})
+    if(NOT TARGET json-c::json-c)
+        add_library(json-c::json-c INTERFACE IMPORTED)
+        set_target_properties(json-c::json-c PROPERTIES
+            INTERFACE_INCLUDE_DIRECTORIES "${JSONC_INCLUDE_DIRS}"
+            INTERFACE_LINK_LIBRARIES "${JSONC_LIBRARIES}"
+        )
+    endif()
+endif()
 
 set(ZITI_HEADER_FILES
         ${PROJECT_SOURCE_DIR}/includes/ziti/errors.h