[CI] Print where we are getting dotnet-install.sh from

Author: dalexsoto

builds/Makefile

@@ -62,6 +62,7 @@ DOTNET_DOWNLOAD_URL?=https://raw.githubusercontent.com/dotnet/install-scripts/87
 DOTNET_DOWNLOAD_URL?=https://dot.net/v1/dotnet-install.sh
 
 dotnet-install.sh: Makefile
+	$(Q) echo "Downloading dotnet-install.sh from $(DOTNET_DOWNLOAD_URL) into $@."
 	$(Q) $(CURL_RETRY) $(DOTNET_DOWNLOAD_URL) --output $@.tmp
 	$(Q) chmod +x $@.tmp
 	$(Q) mv $@.tmp $@