CRIS/LD/testsuite: Add tests for emulation switching

CRIS/LD/testsuite: Add tests for emulation switching

Add tests matching generic ones from ld-archive/archive.exp for explicit
link emulation switching, verifying that correct output is produced from
a link including an archive the format of which is not the default one.

This covers generic BFD code using `cris-aout' and `cris-elf' targets as
ones that permit switching between dissimilar emulations from assembly
through the link.

Only tests for link emulation explicitly specified are included at this
stage, as bugs in BFD currently prevent links from successful completion
that use the default emulation while involving archives in a non-default
format.  Additional tests will be included with a subsequent change that
addresses said bugs.