Output uniform status message before and after src_test()

Output the status messages before and after running src_test()
unconditionally, alike it is done for other src_* phase functions,
rather than in EAPI-default src_test() function. This fixes the issue of
test phase output lacking delimitation whenever a custom src_test()
function was used.
repoman: Do not check for indirect inherits of deprecated eclasses

Complain only about deprecated eclasses that are inherited directly.
Checking indirectly inherited eclasses is pointless since the ebuild
maintainer can't really do anything about it --- it is up to
the maintainer of one of the directly inherited eclasses.
econf: Replace unnecessary 'case' statements with 'if's

Replace the 'case' statements used to match 'configure' output with
simpler pattern-matching 'if's.

Acked-by: Alexander Berntsen <bernalex@gentoo.org>
econf: Add EAPI-conditional arguments via array

Use a dedicated array variable to add EAPI-conditional arguments to
the configure script instead of prepending them to the command
parameters.
Fix off-by-one error in supported EAPI list

Fix the off-by-one error in construction of supported EAPI list that
resulted in EAPI 5 being considered unsupported.
Make eapi_is_supported() reuse _supported_eapis list

Make the eapi_is_supported() function use the generated list of
supported EAPIs rather than partial lists and integer comparison.
Rewrite default ebuild phase setting code

Replace the ebuild phase setting code for EAPI 2 and newer with a
simpler approach; first set proper default_* functions, and call them
within the phase. Disallow calling default_* for other phase functions
than the one being run.