meson: add sparse support

Do not use cgcc; instead, extract compilation commands from compile_commands.json
and invoke sparse directly.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

meson.build

@@ -25,6 +25,13 @@ if host_machine.system() == 'darwin'
   add_languages('objc', required: false, native: false)
 endif
 
+if 'SPARSE_CFLAGS' in config_host
+  run_target('sparse',
+             command: [find_program('scripts/check_sparse.py'),
+                       config_host['SPARSE_CFLAGS'].split(),
+                       'compile_commands.json'])
+endif
+
 configure_file(input: files('scripts/ninjatool.py'),
                output: 'ninjatool',
                configuration: config_host)