Install Ruby mapscript in sitearchdir instead of archdir.

Author: sebastic

mapscript/ruby/CMakeLists.txt

@@ -13,5 +13,5 @@ set_target_properties(${SWIG_MODULE_rubymapscript_REAL_NAME} PROPERTIES PREFIX "
 set_target_properties(${SWIG_MODULE_rubymapscript_REAL_NAME} PROPERTIES OUTPUT_NAME mapscript)
 
 get_target_property(LOC_MAPSCRIPT_LIB ${SWIG_MODULE_rubymapscript_REAL_NAME} LOCATION)
-execute_process(COMMAND ${RUBY_EXECUTABLE} -r rbconfig -e "puts RbConfig::CONFIG['archdir']" OUTPUT_VARIABLE RUBY_ARCHDIR OUTPUT_STRIP_TRAILING_WHITESPACE)
-install(FILES ${LOC_MAPSCRIPT_LIB} DESTINATION ${RUBY_ARCHDIR})
+execute_process(COMMAND ${RUBY_EXECUTABLE} -r rbconfig -e "puts RbConfig::CONFIG['sitearchdir']" OUTPUT_VARIABLE RUBY_SITEARCHDIR OUTPUT_STRIP_TRAILING_WHITESPACE)
+install(FILES ${LOC_MAPSCRIPT_LIB} DESTINATION ${RUBY_SITEARCHDIR})