Xcode: Fix PCH support with Swift & C++

Previously, when a mixed language target ends up with `Swift` as the
`LINKER_LANGUAGE`, the PCH file was not set for the target at all.

Fixes: #21224

1 files changed, 9 insertions, 0 deletions

diff --git a/Tests/SwiftMixPCH/CMain.c b/Tests/SwiftMixPCH/CMain.c
new file mode 100644
index 0000000..4cd78e6
--- /dev/null
+++ b/Tests/SwiftMixPCH/CMain.c
@@ -0,0 +1,9 @@
+#ifndef PCH_VALUE
+#  error "PCH_VALUE not defined"
+#endif
+
+int main(void)
+{
+  const int value = PCH_VALUE;
+  return value == 42 ? 0 : 1;
+}