Include abi.h in the dependency of rubyspec-capiext

Author: nobu

common.mk

@@ -797,7 +797,7 @@ clean-platform distclean-platform realclean-platform:
 
 RUBYSPEC_CAPIEXT = spec/ruby/optional/capi/ext
 RUBYSPEC_CAPIEXT_SRCDIR = $(srcdir)/$(RUBYSPEC_CAPIEXT)
-RUBYSPEC_CAPIEXT_DEPS = $(RUBYSPEC_CAPIEXT_SRCDIR)/rubyspec.h $(RUBY_H_INCLUDES) $(LIBRUBY)
+RUBYSPEC_CAPIEXT_DEPS = $(RUBYSPEC_CAPIEXT_SRCDIR)/rubyspec.h $(RUBY_H_INCLUDES) {$(VPATH)}internal/abi.h $(LIBRUBY)
 RUBYSPEC_CAPIEXT_BUILD = $(enable_shared:yes=rubyspec-capiext)
 
 rubyspec-capiext: build-ext $(DOT_WAIT)