spksrc.publish.mk: add checks for empty variables

[hgy59]

Description

This is another attempt to fix the publishing of packages by github action (broken by #6002)

• make setup-synocommunity triggers "make setup" and this fails when mk/spksrc.test-rules.mk is included
  fixed in common.mk: Fix BASEDIR to manage github-action workspace directory #6066
• add checks for empty PUBLISH_URL and PUBLISH_API_KEY in spksrc.publish.mk
• print PUBLISH_URL variable when publishing

Checklist

• Build rule all-supported completed successfully
• New installation of package completed successfully
• Package upgrade completed successfully (Manually install the package again)
• Package functionality was tested
• Any needed documentation is updated/created

Type of change

• Includes small framework changes

[th0ma7]

I believe what's really needed is the following chage in spksrc.common.mk :

# Set basedir in case called from spkrc/ or from normal sub-dir
# Using github-action it actually is under /github/workspace
ifeq ($(BASEDIR),)
ifeq ($(filter spksrc workspace,$(shell basename $(CURDIR))),)
BASEDIR = ../../
endif
endif

I'll open-up a PR to test that assumption.

[hgy59]

@th0ma7 can you please have a look on the other issue fixed here:
When PUBLISH_URL or PUBLISH_API_KEY is not set, an error was only shown with make publish-all-* and not with make publish-arch-*.
The missing PUBLISH_URL is set to default when make setup-synocommunity was called (and fixed by you in #6066) but the missing PUBLISH_API_KEY error should be handled anyway.
This is also since #6002.

[hgy59]

@th0ma7 If you don't have a solution for PUBLISH_URL and PUBLISH_API_KEY, I will revert the changes in spksrc/Makefile and merge only my changes in mk/spksrc.publish.mk.

[th0ma7]

@th0ma7 If you don't have a solution for PUBLISH_URL and PUBLISH_API_KEY, I will revert the changes in spksrc/Makefile and merge only my changes in mk/spksrc.publish.mk.

I can add something similar to yours, using the comment I just added. Give me a few minutes.