Add a new option 'map' to the ld run_dump_test mechanism. When the
'map' option is given run_dump_test will ensure that there is a
-Map=MAPFILE present in the linker command line, adding one if needed.
The MAPFILE is then compared with the file passed to the new 'map'
option using the regexp_diff function. This should make it slightly
easier to write tests that check the linker mapfile output.
The only test I found that already compares mapfile content is updated
to use the new mechanism.
ld/testsuite/ChangeLog:
* ld-scripts/overlay-size.d: Add 'map' option.
* ld-scripts/overlay-size.exp: Remove manual check of mapfile.
* lib/ld-lib.exp (run_dump_test): Add support for new 'map'
option, checking linker mapfile output.
(is_elf_format): New, extracted from...
* ld-scripts/weak.exp: ...here.
* ld-scripts/overlay-size.exp: New test.
* ld-scripts/overlay-size.[tsd],
* ld-scripts/overlay-size-map.d: New files for it.
