[Bug target/65296] New: [avr] fix various issues with specs file generation

[gjl at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65296

            Bug ID: 65296
           Summary: [avr] fix various issues with specs file generation
           Product: gcc
           Version: 5.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: gjl at gcc dot gnu.org
            Target: avr

Fix various problems like:

Fix wrong function parameter types, fix build warnings, handle -march= in
DRIVER_SELF_SPEC, fix non-existing %-code, add avr-libc awareness as of
PR54461, do not use avr-libc features if configured with --with-avrlibc=no,
code clean-up, remove dead files, code and macros ...