drop unneeded define

Change-Id: I3a61e345593959c47b62ba2da97abafca24ee0e8
Reviewed-on: https://gerrit.libreoffice.org/55754Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: David Tardon <dtardon@redhat.com>

external/libstaroffice/Library_staroffice.mk

@@ -27,7 +27,6 @@ $(eval $(call gb_Library_add_defs,staroffice,\
 	-DBUILD_STOFF \
 	-D_WINDLL \
 	-DNDEBUG \
-	-DSHAREDPTR_STD \
 ))
 
 $(eval $(call gb_Library_add_generated_exception_objects,staroffice,\