Add translation files only if the NLS knob is set

--- src/gdal/CMakeLists.txt.orig	2019-12-05 06:33:57 UTC
+++ src/gdal/CMakeLists.txt
@@ -36,7 +36,9 @@ set(MAPPER_GDAL_SOURCES
   mapper-osmconf.ini
 )
 	
-mapper_translations_sources(${MAPPER_GDAL_HEADERS} ${MAPPER_GDAL_SOURCES})
+if(Mapper_WITH_NLS)
+	mapper_translations_sources(${MAPPER_GDAL_HEADERS} ${MAPPER_GDAL_SOURCES})
+endif()
 
 add_library(mapper-gdal STATIC ${MAPPER_GDAL_HEADERS} ${MAPPER_GDAL_SOURCES} "${PROJECT_BINARY_DIR}/gdal/mapper-osmconf.ini")