[Bug #21792] Build rubyspec-capiext only when excuting test-spec

rubyspec-capiext is only needed for running specs, not for building or
installing Ruby.

common.mk

@@ -804,6 +804,7 @@ 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_BUILD = $(enable_shared:yes=rubyspec-capiext)
 
 rubyspec-capiext: build-ext $(DOT_WAIT)
 # make-dependent rules should be included after this and built after build-ext.
@@ -905,7 +906,7 @@ test: test-short
 
 # Separate to skip updating encs and exts by `make -o test-precheck`
 # for GNU make.
-test-precheck: $(ENCSTATIC:static=lib)encs exts PHONY $(DOT_WAIT)
+test-precheck: $(ENCSTATIC:static=lib)encs $(RUBYSPEC_CAPIEXT_BUILD) exts PHONY $(DOT_WAIT)
 yes-test-all-precheck: programs $(DOT_WAIT) test-precheck
 
 PRECHECK_TEST_ALL = yes-test-all-precheck

defs/gmake.mk

@@ -529,11 +529,7 @@ RUBYSPEC_CAPIEXT_SO := $(patsubst %.c,$(RUBYSPEC_CAPIEXT)/%.$(DLEXT),$(notdir $(
 rubyspec-capiext: $(RUBYSPEC_CAPIEXT_SO)
 	@ $(NULLCMD)
 
-ifeq ($(ENABLE_SHARED),yes)
-exts: rubyspec-capiext
-endif
-
-spec/%/ spec/%_spec.rb: programs exts PHONY
+spec/%/ spec/%_spec.rb: programs exts $(RUBYSPEC_CAPIEXT_BUILD) PHONY
 	+$(RUNRUBY) -r./$(arch)-fake $(srcdir)/spec/mspec/bin/mspec-run -B $(srcdir)/spec/default.mspec $(SPECOPTS) $(patsubst %,$(srcdir)/%,$@)
 
 ruby.pc: $(filter-out ruby.pc,$(ruby_pc))

win32/Makefile.sub

@@ -1425,8 +1425,6 @@ rubyspec-capiext: $(RUBYSPEC_CAPIEXT_EXTS)
 	$(Q)$(LDSHARED) -Fe$(@) -Fo$(*).obj $(INCFLAGS) $(CFLAGS) $(CPPFLAGS) $< $(LIBRUBYARG) -link $(DLDFLAGS) $(XLDFLAGS) $(LIBS) $(LOCAL_LIBS) -implib:$*.lib -pdb:$*.pdb -def:$*.def
 	$(Q)$(RM) $*.def $*.exp $*.lib $*.obj $*.pdb
 
-exts: rubyspec-capiext
-
 yesterday:
 	(set TZ=UTC-9) && \
 	for /f "usebackq" %H in \