tests/qapi-schema: Switch member name clash test to struct

Test args-name-clash covers command parameter name clash.  This
effectively covers struct member name clash as well.  The next commit
will make parameter name clash impossible.  Convert args-name-clash
from testing command to testing a struct, and rename it to
struct-member-name-clash.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20210323094025.3569441-26-armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
[Commit message typo fixed]

tests/qapi-schema/args-name-clash.err

-args-name-clash.json: In command 'oops':
-args-name-clash.json:4: parameter 'a_b' collides with parameter 'a-b'

tests/qapi-schema/meson.build

@@ -30,7 +30,6 @@ schemas = [
   'args-member-array-bad.json',
   'args-member-case.json',
   'args-member-unknown.json',
-  'args-name-clash.json',
   'args-union.json',
   'args-unknown.json',
   'bad-base.json',
@@ -177,6 +176,7 @@ schemas = [
   'struct-member-if-invalid.json',
   'struct-member-invalid-dict.json',
   'struct-member-invalid.json',
+  'struct-member-name-clash.json',
   'trailing-comma-list.json',
   'trailing-comma-object.json',
   'type-bypass-bad-gen.json',

tests/qapi-schema/struct-member-name-clash.err

+struct-member-name-clash.json: In struct 'Oops':
+struct-member-name-clash.json:4: member 'a_b' collides with member 'a-b'

tests/qapi-schema/args-name-clash.json → tests/qapi-schema/struct-member-name-clash.json

 # C member name collision
 # Reject members that clash when mapped to C names (we would have two 'a_b'
 # members).
-{ 'command': 'oops', 'data': { 'a-b': 'str', 'a_b': 'str' } }
+{ 'struct': 'Oops', 'data': { 'a-b': 'str', 'a_b': 'str' } }