[3.10] gh-145455: Show output of blurb & sphinx-build version commands (GH-145457) (#145489)

Co-authored-by: Petr Viktorin <encukou@gmail.com>

Author: miss-islington

Doc/Makefile

@@ -56,7 +56,7 @@ build:
 	@if [ -f  ../Misc/NEWS ] ; then \
 		echo "Using existing Misc/NEWS file"; \
 		cp ../Misc/NEWS build/NEWS; \
-	elif $(BLURB) help >/dev/null 2>&1 && $(SPHINXBUILD) --version >/dev/null 2>&1; then \
+	elif $(BLURB) --version && $(SPHINXBUILD) --version ; then \
 		if [ -d ../Misc/NEWS.d ]; then \
 			echo "Building NEWS from Misc/NEWS.d with blurb"; \
 			$(BLURB) merge -f build/NEWS; \