Make the CMake build set the absolute RPATH in the shared library on macOS.

* CMakeLists.txt (target serf_shared): Set the INSTALL_NAME_DIR property.
* build/SerfPlatform.cmake: Set CMAKE_MACOSX_RPATH to FALSE on OSX.


git-svn-id: https://svn.apache.org/repos/asf/serf/trunk@1842100 13f79535-47bb-0310-9956-ffa450edef68
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 3a6f59f..7fd0051 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -302,7 +302,8 @@
   set_target_properties(serf_shared
                         PROPERTIES
                         VERSION ${SERF_VERSION}
-                        SOVERSION ${SERF_SOVERSION})
+                        SOVERSION ${SERF_SOVERSION}
+                        INSTALL_NAME_DIR "${CMAKE_INSTALL_PREFIX}/lib")
   set(SERF_TARGETS "serf_shared")
 
   if(SERF_WINDOWS)
diff --git a/build/SerfPlatform.cmake b/build/SerfPlatform.cmake
index b7ffe1a..9a2c4b4 100644
--- a/build/SerfPlatform.cmake
+++ b/build/SerfPlatform.cmake
@@ -19,6 +19,7 @@
 
 if(${CMAKE_SYSTEM_NAME} MATCHES  "Darwin")
   set(SERF_DARWIN TRUE)
+  set(CMAKE_MACOSX_RPATH FALSE)
   message(STATUS "Target platform is Darwin (macOS)")
 elseif(${CMAKE_SYSTEM_NAME} MATCHES "Linux")
   set(SERF_LINUX TRUE)