Use standard CMake variables - static/shared lib.

Replace JSONCPP_LIB_BUILD_SHARED => BUILD_SHARED_LIBS
Replace JSONCPP_LIB_BUILD_STATIC => BUILD_STATIC_LIBS
Removed workaround  open-source-parsers#51
Removed OPTION for shared/static in this file.

Author: ya1gaurav

src/lib_json/CMakeLists.txt

@@ -1,10 +1,3 @@
-OPTION(JSONCPP_LIB_BUILD_SHARED "Build jsoncpp_lib as a shared library." OFF)
-OPTION(JSONCPP_LIB_BUILD_STATIC "Build jsoncpp_lib static library." ON)
-
-IF(BUILD_SHARED_LIBS)
-  SET(JSONCPP_LIB_BUILD_SHARED ON)
-ENDIF(BUILD_SHARED_LIBS)
-
 if( CMAKE_COMPILER_IS_GNUCXX )
   #Get compiler version.
   execute_process( COMMAND ${CMAKE_CXX_COMPILER} -dumpversion
@@ -46,7 +39,7 @@ ELSE(JSONCPP_WITH_CMAKE_PACKAGE)
     SET(INSTALL_EXPORT)
 ENDIF(JSONCPP_WITH_CMAKE_PACKAGE)
 
-IF(JSONCPP_LIB_BUILD_SHARED)
+IF(BUILD_SHARED_LIBS)
     ADD_DEFINITIONS( -DJSON_DLL_BUILD )
     ADD_LIBRARY(jsoncpp_lib SHARED ${PUBLIC_HEADERS} ${jsoncpp_sources})
     SET_TARGET_PROPERTIES( jsoncpp_lib PROPERTIES VERSION ${JSONCPP_VERSION} SOVERSION ${JSONCPP_VERSION_MAJOR})
@@ -65,7 +58,7 @@ IF(JSONCPP_LIB_BUILD_SHARED)
 
 ENDIF()
 
-IF(JSONCPP_LIB_BUILD_STATIC)
+IF(BUILD_STATIC_LIBS)
     ADD_LIBRARY(jsoncpp_lib_static STATIC ${PUBLIC_HEADERS} ${jsoncpp_sources})
     SET_TARGET_PROPERTIES( jsoncpp_lib_static PROPERTIES VERSION ${JSONCPP_VERSION} SOVERSION ${JSONCPP_VERSION_MAJOR})
     SET_TARGET_PROPERTIES( jsoncpp_lib_static PROPERTIES OUTPUT_NAME jsoncpp )