more portable OS X library install names

lib/CMakeLists.txt

@@ -104,7 +104,7 @@ set(lib_HEADERS
 )
 
 add_library(vcmi SHARED ${lib_SRCS} ${lib_HEADERS})
-set_target_properties(vcmi PROPERTIES XCODE_ATTRIBUTE_LD_DYLIB_INSTALL_NAME "@executable_path/libvcmi.dylib")
+set_target_properties(vcmi PROPERTIES XCODE_ATTRIBUTE_LD_DYLIB_INSTALL_NAME "@rpath/libvcmi.dylib")
 target_link_libraries(vcmi minizip ${Boost_LIBRARIES} ${SDL_LIBRARY} ${ZLIB_LIBRARIES} ${RT_LIB} ${DL_LIB})
 
 set_target_properties(vcmi PROPERTIES ${PCH_PROPERTIES})

lib/minizip/CMakeLists.txt

@@ -12,7 +12,7 @@ set(lib_SRCS
 )
 
 add_library(minizip SHARED ${lib_SRCS})
-set_target_properties(minizip PROPERTIES XCODE_ATTRIBUTE_LD_DYLIB_INSTALL_NAME "@executable_path/libminizip.dylib")
+set_target_properties(minizip PROPERTIES XCODE_ATTRIBUTE_LD_DYLIB_INSTALL_NAME "@rpath/libminizip.dylib")
 target_link_libraries(minizip ${ZLIB_LIBRARIES})
 
 if (NOT APPLE) # Already inside vcmiclient bundle