meson: subprojects: replace berkeley-{soft,test}float-3 with wraps

Unlike other subprojects, these require an overlay directory to include
meson rules to build the libraries.  The rules are basically lifted
from tests/fp/meson.build, with a few changes to create platform.h
and publish a dependency.

The build defines are passed through a subproject option, and posted
back to users of the library via the dependency's compile_args.

The only remaining user of GIT_SUBMODULES and GIT_SUBMODULES_ACTION
is roms/SLOF, which is used to build pc-bios/s390-ccw.  All other
roms submodules are only present to satisfy the license on pre-built
firmware blobs.

Best reviewed with --color-moved.

Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

scripts/archive-source.sh

@@ -26,8 +26,7 @@ sub_file="${sub_tdir}/submodule.tar"
 # independent of what the developer currently has initialized
 # in their checkout, because the build environment is completely
 # different to the host OS.
-subprojects="dtc keycodemapdb libvfio-user"
-submodules="tests/fp/berkeley-softfloat-3 tests/fp/berkeley-testfloat-3"
+subprojects="dtc keycodemapdb libvfio-user berkeley-softfloat-3 berkeley-testfloat-3"
 sub_deinit=""
 
 function cleanup() {
@@ -51,25 +50,6 @@ function tree_ish() {
 
 git archive --format tar "$(tree_ish)" > "$tar_file"
 test $? -ne 0 && error "failed to archive qemu"
-for sm in $submodules; do
-    status="$(git submodule status "$sm")"
-    smhash="${status#[ +-]}"
-    smhash="${smhash%% *}"
-    case "$status" in
-        -*)
-            sub_deinit="$sub_deinit $sm"
-            git submodule update --init "$sm"
-            test $? -ne 0 && error "failed to update submodule $sm"
-            ;;
-        +*)
-            echo "WARNING: submodule $sm is out of sync"
-            ;;
-    esac
-    (cd $sm; git archive --format tar --prefix "$sm/" $(tree_ish)) > "$sub_file"
-    test $? -ne 0 && error "failed to archive submodule $sm ($smhash)"
-    tar --concatenate --file "$tar_file" "$sub_file"
-    test $? -ne 0 && error "failed append submodule $sm to $tar_file"
-done
 
 for sp in $subprojects; do
     meson subprojects download $sp