Clean up includes

Clean up includes

Clean up includes so that osdep.h is included first and headers
which it implies are not included manually.

This commit was created with scripts/clean-includes, with the changes
to the following files manually reverted:

    contrib/libvhost-user/libvhost-user-glib.h
    contrib/libvhost-user/libvhost-user.c
    contrib/libvhost-user/libvhost-user.h
    linux-user/mips64/cpu_loop.c
    linux-user/mips64/signal.c
    linux-user/sparc64/cpu_loop.c
    linux-user/sparc64/signal.c
    linux-user/x86_64/cpu_loop.c
    linux-user/x86_64/signal.c
    slirp/src/*
    target/s390x/gen-features.c
    tests/fp/platform.h
    tests/migration/s390x/a-b-bios.c
    tests/test-rcu-simpleq.c
    tests/test-rcu-tailq.c
    tests/uefi-test-tools/UefiTestToolsPkg/BiosTablesTest/BiosTablesTest.c

We're in the process of spinning out slirp/.  tests/fp/platform.h is
has to include qemu/osdep.h because tests/fp/berkeley-softfloat-3/ and
tests/fp/berkeley-testfloat-3/ don't.  tests/uefi-test-tools/ is guest
software.  The remaining reverts are the same as in commit
b7d89466dde.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20190313162812.8885-1-armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
[Revert change to tests/fp/platform.h, adjust commit message]