connectivity/kab (indirectly) depends on boost_header

...at least via KDriver.cxx -> tools/diagnose_ex.h -> boost/noncopyable.hpp
(kab1) and KStatement.cxx -> KStatement.hxx -> connectivity/sqliterator.hxx ->
boost/shared_ptr.hpp (kabdrv1).  Becomes evident when building
--with-system-boost --with-boost=... on a machine with no system-wide Boost
installation.  Not sure solving those problems this way is the best approach,
though.

Change-Id: Ida72362596aaac076efc4e1faab41fa47013975f

connectivity/Library_kab1.mk

@@ -27,7 +27,10 @@
 
 $(eval $(call gb_Library_Library,kab1))
 
-$(eval $(call gb_Library_use_externals,kab1,kde))
+$(eval $(call gb_Library_use_externals,kab1, \
+    boost_headers \
+    kde \
+))
 
 $(eval $(call gb_Library_set_componentfile,kab1,connectivity/source/drivers/kab/kab1))
 

connectivity/Library_kabdrv1.mk

@@ -34,6 +34,7 @@ $(eval $(call gb_Library_use_packages,kabdrv1,\
 $(eval $(call gb_Library_use_sdk_api,kabdrv1))
 
 $(eval $(call gb_Library_use_externals,kabdrv1,\
+	boost_headers \
 	kde \
 ))