Silence "object has no symbols" warnings from ranlib on macOS.

* auth/auth_spnego.c, auth/auth_spnego_gss.c, auth/auth_spnego_sspi.c:
   Make sure each object file compiled from these sources contains at
   least one public symbol.


git-svn-id: https://svn.apache.org/repos/asf/serf/trunk@1834228 13f79535-47bb-0310-9956-ffa450edef68
diff --git a/auth/auth_spnego.c b/auth/auth_spnego.c
index bf560e7..acbba78 100644
--- a/auth/auth_spnego.c
+++ b/auth/auth_spnego.c
@@ -676,4 +676,7 @@
 };
 #endif /* #ifdef WIN32 */
 
+#else  /* SERF_HAVE_SPNEGO */
+/* Prevent "object has no symbols" warnings from ranlib on macOS. */
+const long serf__fake__auth_spnego_c = 0xdeadbeef;
 #endif /* SERF_HAVE_SPNEGO */
diff --git a/auth/auth_spnego_gss.c b/auth/auth_spnego_gss.c
index 80b54fd..fe3e7d6 100644
--- a/auth/auth_spnego_gss.c
+++ b/auth/auth_spnego_gss.c
@@ -231,4 +231,7 @@
     }
 }
 
+#else  /* SERF_USE_GSSAPI */
+/* Prevent "object has no symbols" warnings from ranlib on macOS. */
+const long serf__fake__auth_spnego_gas_c = 0xdeadbeef;
 #endif /* SERF_USE_GSSAPI */
diff --git a/auth/auth_spnego_sspi.c b/auth/auth_spnego_sspi.c
index 0310492..48035a9 100644
--- a/auth/auth_spnego_sspi.c
+++ b/auth/auth_spnego_sspi.c
@@ -300,4 +300,7 @@
     }
 }
 
+#else  /* SERF_USE_SSPI */
+/* Prevent "object has no symbols" warnings from ranlib on macOS. */
+const long serf__fake__auth_spnego_sspi_c = 0xdeadbeef;
 #endif /* SERF_USE_SSPI */