Fix build with recent cmake

The extra dot after the %cmake macro causes build failure with the
recent cmake versions. Although this is regression on cmake side, it
looks safe to remove that dot as workaround, because the macro uses
"-S ." already.

Related: https://bugzilla.redhat.com/show_bug.cgi?id=2057738

freerdp.spec

@@ -216,7 +216,7 @@ find . -name "*.c" -exec chmod 664 {} \;
     -DARM_FP_ABI=soft \
     -DWITH_NEON=OFF \
 %endif
-    .
+    %{nil}
 
 %cmake_build