odk: don't run make with LD_LIBRARY_PATH set

In a build with -fsanitize=address, this fails with:

Change-Id: If8581363a395af78bbbe00dd656290aea53af330
make: symbol lookup error: instdir/program/libfreebl3.so: undefined symbol: __asan_option_detect_stack_use_after_return

odk/CustomTarget_build-examples.mk

@@ -91,6 +91,7 @@ $(call gb_CustomTarget_get_target,odk/build-examples): \
         $(call gb_CustomTarget_get_workdir,odk/build-examples)/setsdkenv
 	$(call gb_Output_announce,$(subst $(WORKDIR)/,,$@),$(true),CHK,1)
 	(. $< \
+		&& unset LD_LIBRARY_PATH \
         && export \
             UserInstallation=$(call gb_Helper_make_url,$(call gb_CustomTarget_get_workdir,odk/build-examples)/user) \
         $(foreach my_dir,$(my_example_dirs), \