tde_create_translated_desktop: Prevent FTBFS if the length

of CMAKE_BINARY_DIR is longer than the tested _basename.

Signed-off-by: Slávek Banko <slavek.banko@axis.cz>
(cherry picked from commit 111a08942a)

modules/TDEMacros.cmake

@@ -1914,7 +1914,12 @@ macro( tde_create_translated_desktop )
     get_filename_component( _basename ${_src} ABSOLUTE )
     get_filename_component( _basedir ${_basename} PATH )
     file( RELATIVE_PATH _sourcename "${CMAKE_SOURCE_DIR}" "${_basename}" )
-    string( SUBSTRING "${_basename}" 0 ${CMAKE_BINARY_DIR_LEN} _basedir_prefix )
+    string( LENGTH "${_basename}" _basename_len )
+    if( ${_basename_len} LESS ${CMAKE_BINARY_DIR_LEN} )
+      set( _basedir_prefix "${CMAKE_SOURCE_DIR}" )
+    else( )
+      string( SUBSTRING "${_basename}" 0 ${CMAKE_BINARY_DIR_LEN} _basedir_prefix )
+    endif( )
     if( ${_basedir_prefix} STREQUAL "${CMAKE_BINARY_DIR}" )
       file( RELATIVE_PATH _basename "${CMAKE_CURRENT_BINARY_DIR}" "${_basename}" )
       set( _binsuffix ".out" )