build: link test programs with static libraries

Many of the test programs directly access internal symbols not
exported from the shared libraries.  This allows tests to run
when configured with shared libraries.
Signed-off-by: Mans Rullgard <mans@mansr.com>

library.mak

@@ -92,6 +92,7 @@ endef
 $(eval $(RULES))
 
 $(EXAMPLES) $(TESTPROGS) $(TOOLS): $(THIS_LIB) $(DEP_LIBS)
+$(TESTPROGS): $(SUBDIR)$(LIBNAME)
 
 examples: $(EXAMPLES)
 testprogs: $(TESTPROGS)