Create symlink for base soname for libraries with release number in the name

as a separate target instead of POST_BUILD command. This prevents the
command from being executed multiple times and thus FTBFS.

Signed-off-by: Slávek Banko <slavek.banko@axis.cz>
(cherry picked from commit e22f5ace4a)

modules/TDEMacros.cmake

@@ -886,8 +886,22 @@ macro( tde_add_library _arg_target )
         get_target_property( _soversion ${_target} SOVERSION )
         set( _soname "${_soname}.${_soversion}" )
       endif( )
-      add_custom_command( TARGET ${_target} POST_BUILD
-        COMMAND ln -s ${_soname} "${CMAKE_CURRENT_BINARY_DIR}/${_soname_base}" )
+      if( NOT _exclude_from_all )
+        add_custom_command(
+          OUTPUT "${CMAKE_CURRENT_BINARY_DIR}/${_soname_base}"
+          COMMAND ln -s ${_soname} "${CMAKE_CURRENT_BINARY_DIR}/${_soname_base}"
+          DEPENDS ${_target}
+        )
+        add_custom_target(
+          ${_target}+base-so ALL
+          DEPENDS "${CMAKE_CURRENT_BINARY_DIR}/${_soname_base}"
+        )
+      else( )
+        add_custom_command(
+          TARGET ${_target} POST_BUILD
+          COMMAND ln -s ${_soname} "${CMAKE_CURRENT_BINARY_DIR}/${_soname_base}"
+        )
+      endif( )
       install( FILES "${CMAKE_CURRENT_BINARY_DIR}/${_soname_base}" DESTINATION ${_destination} )
     endif( )