libgluonutil: simplify CMakeLists.txt

libgluonutil is not usable outside the OpenWrt/LEDE environment anyways, so
it doesn't make much sense to make the CMakeLists.txt overly generic.

package/libgluonutil/src/CMakeLists.txt

 cmake_minimum_required(VERSION 2.6)
 
-set(CMAKE_MODULE_PATH ${CMAKE_CURRENT_SOURCE_DIR})
-
 project(libgluonutil C)
 
-set(LIBDIR "lib${LIB_SUFFIX}")
-
-find_package(JSON_C REQUIRED)
-
 set_property(DIRECTORY PROPERTY COMPILE_DEFINITIONS _GNU_SOURCE)
 
 add_library(gluonutil SHARED libgluonutil.c)
-set_property(TARGET gluonutil PROPERTY COMPILE_FLAGS "-Wall -std=c99 ${JSON_C_CFLAGS_OTHER}")
-set_property(TARGET gluonutil PROPERTY LINK_FLAGS "${JSON_C_LDFLAGS_OTHER}")
-set_property(TARGET gluonutil APPEND PROPERTY INCLUDE_DIRECTORIES ${JSON_C_INCLUDE_DIR})
-target_link_libraries(gluonutil ${JSON_C_LIBRARIES})
+set_property(TARGET gluonutil PROPERTY COMPILE_FLAGS "-Wall -std=c99")
+target_link_libraries(gluonutil json-c)
 install(TARGETS gluonutil
-  ARCHIVE DESTINATION ${LIBDIR}
-  LIBRARY DESTINATION ${LIBDIR}
+  ARCHIVE DESTINATION lib
+  LIBRARY DESTINATION lib
 )
 
-
 install(FILES ${CMAKE_CURRENT_SOURCE_DIR}/libgluonutil.h DESTINATION include)

package/libgluonutil/src/FindJSON_C.cmake

-# Defines the following variables:
-#  JSON_C_FOUND
-#  JSON_C_INCLUDE_DIR
-#  JSON_C_LIBRARIES
-#  JSON_C_CFLAGS_OTHER
-#  JSON_C_LDFLAGS_OTHER
-
-
-find_package(PkgConfig REQUIRED QUIET)
-
-pkg_check_modules(_JSON_C json-c)
-
-find_path(JSON_C_INCLUDE_DIR NAMES json-c/json.h HINTS ${_JSON_C_INCLUDE_DIRS})
-find_library(JSON_C_LIBRARIES NAMES json-c HINTS ${_JSON_C_LIBRARY_DIRS})
-
-set(JSON_C_CFLAGS_OTHER "${_JSON_C_CFLAGS_OTHER}" CACHE STRING "Additional compiler flags for json-c")
-set(JSON_C_LDFLAGS_OTHER "${_JSON_C_LDFLAGS_OTHER}" CACHE STRING "Additional linker flags for json-c")
-
-find_package_handle_standard_args(JSON_C REQUIRED_VARS JSON_C_LIBRARIES JSON_C_INCLUDE_DIR)
-mark_as_advanced(JSON_C_INCLUDE_DIR JSON_C_LIBRARIES JSON_C_CFLAGS_OTHER JSON_C_LDFLAGS_OTHER)