Fix Xcode targets in subdirs.

mesonbuild/backend/xcodebackend.py

diff --git a/mesonbuild/backend/xcodebackend.py b/mesonbuild/backend/xcodebackend.py
index c49f01d..b37ee2f 100644
--- a/mesonbuild/backend/xcodebackend.py
+++ b/mesonbuild/backend/xcodebackend.py
@@ -431,10 +431,8 @@
             for s in t.sources:
                 if isinstance(s, mesonlib.File):
                     s = os.path.join(s.subdir, s.fname)
-
                 if not isinstance(s, str):
                     continue
-                s = os.path.join(t.subdir, s)
                 sdict = PbxDict()
                 idval = self.buildfile_ids[(tname, s)]
                 fileref = self.fileref_ids[(tname, s)]
@@ -495,10 +493,8 @@
             for s in t.sources:
                 if isinstance(s, mesonlib.File):
                     s = os.path.join(s.subdir, s.fname)
-
                 if not isinstance(s, str):
                     continue
-                s = os.path.join(t.subdir, s)
                 idval = self.fileref_ids[(tname, s)]
                 fullpath = os.path.join(self.environment.get_source_dir(), s)
                 src_dict = PbxDict()

test cases/common/11 subdir/subdir/meson.build

diff --git a/test cases/common/11 subdir/subdir/meson.build b/test cases/common/11 subdir/subdir/meson.build
index 5b399f0..d84ec13 100644
--- a/test cases/common/11 subdir/subdir/meson.build
+++ b/test cases/common/11 subdir/subdir/meson.build
@@ -1 +1,2 @@
-executable('prog', 'prog.c')
+prog = executable('prog', 'prog.c')
+test('subdirprog', prog)