[Bug target/61996] New: [SH] -musermode conflicts with -matomic-model=soft-imask

["olegendo at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61996

            Bug ID: 61996
           Summary: [SH] -musermode conflicts with
                    -matomic-model=soft-imask
           Product: gcc
           Version: 4.10.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: olegendo at gcc dot gnu.org
            Target: sh*-*-*

Originally reported log:

checking for suffix of object files... configure: error: in
`/data/fedora/cross-gcc/gcc-4.9.1-20140717/sh-linux-gnu/sh-linux-gnu/libgcc':
configure: error: cannot compute suffix of object files: cannot compile

[in config.log]
conftest.c:1:0: error: cannot use atomic model soft-imask in user mode

It seems that when building for SH1/SH2/SH2A sh-linux, the -musermode option is
set by default and then conflicts with the default -matomic-model=soft-imask
setting.

Proposed fix:
- musermode should have no effect on SH targets that don't have user/privileged
modes (SH1, SH2, SH2A).

- mno-usermode should be added to allow disabling user mode restrictions when
it is enabled by default (i.e. in sh-*-linux case).