CMakeLists.txt: allow CMAKE_INSTALL_RPATH to be set empty
this allows the user to override the default non-empty value added in:
CMake: set rpath for shared objects
Fixed: webp:592
@@ -101,7 +101,7 @@ endif()
include(cmake/deps.cmake)
include(GNUInstallDirs)
-if(BUILD_SHARED_LIBS AND NOT CMAKE_INSTALL_RPATH)
+if(BUILD_SHARED_LIBS AND NOT DEFINED CMAKE_INSTALL_RPATH)
# Set the rpath to match autoconf/libtool behavior. Note this must be set
# before target creation.
set(CMAKE_INSTALL_RPATH "${CMAKE_INSTALL_PREFIX}/${CMAKE_INSTALL_LIBDIR}")
