allow builder to specify RPATH in a cmake variable if they so choose …

…- cmake -DYAJL_RPATH_PREFIX=/home/y ..

CMakeLists.txt

@@ -38,6 +38,15 @@ SET (YAJL_MICRO 10)
 
 SET (YAJL_DIST_NAME "yajl-${YAJL_MAJOR}.${YAJL_MINOR}.${YAJL_MICRO}")
 
+# RPATH handling.  When YAJL_RPATH_PREFIX cmake var is set, we'll use that
+# base for rpath instead of CMAKE_INSTALL_PREFIX
+IF (YAJL_RPATH_PREFIX)
+  SET(CMAKE_SKIP_BUILD_RPATH  TRUE)
+  SET(CMAKE_BUILD_WITH_INSTALL_RPATH TRUE) 
+  SET(CMAKE_INSTALL_RPATH "${YAJL_RPATH_PREFIX}/lib")
+  SET(CMAKE_INSTALL_RPATH_USE_LINK_PATH TRUE)
+ENDIF (YAJL_RPATH_PREFIX)
+
 IF (NOT CMAKE_BUILD_TYPE)
   SET(CMAKE_BUILD_TYPE "Release")
 ENDIF (NOT CMAKE_BUILD_TYPE)