populate_sdk_ext.bbclass: only overwirte lsb string if uninative is used

Overwriting the lsb string without inheriting from uninative causes
shared state cache entries to end up in the wrong path where they are
not beeing picked up by the extensible SDK environment.

(From OE-Core rev: 6a4c83919f27f0f552e9b79aed11e3da6791b7e9)

Signed-off-by: Timon Bergelt <timon.bergelt@pm.me>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/classes-recipe/populate_sdk_ext.bbclass

@@ -494,7 +494,7 @@ def prepare_locked_cache(d, baseoutpath, derivative, conf_initpath):
     bb.utils.remove(sstate_out, True)
 
     # uninative.bbclass sets NATIVELSBSTRING to 'universal%s' % oe.utils.host_gcc_version(d)
-    fixedlsbstring = "universal%s" % oe.utils.host_gcc_version(d)
+    fixedlsbstring = "universal%s" % oe.utils.host_gcc_version(d) if bb.data.inherits_class('uninative', d) else ""
 
     sdk_include_toolchain = (d.getVar('SDK_INCLUDE_TOOLCHAIN') == '1')
     sdk_ext_type = d.getVar('SDK_EXT_TYPE')