We'll have to link to libstdc++ if linking to ICU, so disable test for now

We have to get rid of the ICU in main lib.  Still thinking about best way
to do it.

src/Makefile.am

@@ -96,8 +96,11 @@ main_SOURCES = main.cc
 main_CPPFLAGS = $(HBCFLAGS)
 main_LDADD = libharfbuzz.la $(HBLIBS)
 
-TESTS = \
-	check-libstdc++.sh \
-	$(NULL)
+TESTS =
+
+if HAVE_ICU
+else
+TESTS += check-libstdc++.sh
+endif
 
 -include $(top_srcdir)/git.mk