tests/fp: Do not build softfloat3 tests if TCG is disabled

Technically we don't need the TCG accelerator to run the
softfloat3 tests. However it is unlikely an interesting
build combination. Developers using softfloat3 likely use
TCG too. Similarly, developers disabling TCG shouldn't
mind much about softfloat3 tests.

This reduces a non-TCG build by 474 objects!

Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Message-Id: <20220204152924.6253-3-f4bug@amsat.org>
Signed-off-by: Thomas Huth <thuth@redhat.com>

tests/fp/meson.build

+if 'CONFIG_TCG' not in config_all
+  subdir_done()
+endif
 # There are namespace pollution issues on Windows, due to osdep.h
 # bringing in Windows headers that define a FLOAT128 type.
 if targetos == 'windows'