Removed GPR_POSIX_FILE, and changed the files that used it
diff --git a/build.yaml b/build.yaml
index 39514bd..e3afcd6 100644
--- a/build.yaml
+++ b/build.yaml
@@ -466,8 +466,7 @@
   - src/core/lib/security/credentials/credentials.c
   - src/core/lib/security/credentials/credentials_metadata.c
   - src/core/lib/security/credentials/fake/fake_credentials.c
-  - src/core/lib/security/credentials/google_default/credentials_posix.c
-  - src/core/lib/security/credentials/google_default/credentials_windows.c
+  - src/core/lib/security/credentials/google_default/credentials_generic.c
   - src/core/lib/security/credentials/google_default/google_default_credentials.c
   - src/core/lib/security/credentials/iam/iam_credentials.c
   - src/core/lib/security/credentials/jwt/json_token.c