Add support for relative paths in '_tde_internal_setup_path'

Signed-off-by: Michele Calgaro <michele.calgaro@yahoo.it>
(cherry picked from commit 71fe92911c)

modules/TDESetupPaths.cmake

@@ -15,10 +15,14 @@
 
 macro( _tde_internal_setup_path _path _default _comment )
   if( DEFINED ${_path} )
-    set( ${_path} "${${_path}}" CACHE PATH "${_comment}" )
-  else( DEFINED ${_path} )
+    if( IS_ABSOLUTE ${${_path}} )
+      set( ${_path} "${${_path}}" CACHE PATH "${_comment}" FORCE )
+    else( )
+      set( ${_path} "${CMAKE_INSTALL_PREFIX}/${${_path}}" CACHE PATH "${_comment}" FORCE )
+    endif( )
+  else( )
     set( ${_path} "${_default}" )
-  endif( DEFINED ${_path} )
+  endif( )
 endmacro( _tde_internal_setup_path )