cmake: Set CMAKE_INSTALL_RPATH from top-level CMakeLists.txt

There is no need to assign this variable every time macros.cmake is
included.

CMakeLists.txt

@@ -75,6 +75,11 @@ endif()
 INCLUDE(cmake/macros.cmake)
 INCLUDE(cmake/checks.cmake)
 
+set(CMAKE_INSTALL_RPATH
+   ${CMAKE_INSTALL_RPATH}
+   ${CMAKE_INSTALL_PREFIX}/${SD_LIBDIR}/lib
+)
+
 CHECK_HEADERS_H()
 CHECK_FUNCTIONS()
 CHECK_LIBRARIES()

cmake/macros.cmake

@@ -82,7 +82,6 @@ STRING(REGEX REPLACE "^(.*[^/])/*$" "\\1" SD_LOCALDIR_TMP ${SD_LOCALDIR})
 SET(SD_LOCALDIR ${SD_LOCALDIR_TMP})
 
 SET(CMAKE_MODULE_PATH ${CMAKE_MODULE_PATH} ${CMAKE_CURRENT_LIST_DIR})
-SET(CMAKE_INSTALL_RPATH ${CMAKE_INSTALL_PREFIX}/${SD_LIBDIR}/lib)
 
 # Configuration options macros.
 INCLUDE(${CMAKE_CURRENT_LIST_DIR}/options.cmake)