maint: address syntax-check issues.

* examples/calc++/local.mk: Space changes.
* src/files.c: Avoid unmarked_diagnostics.
* src/output.c: Remove useless include.

src/files.c

@@ -139,7 +139,10 @@ xfdopen (int fd, char const *mode)
 {
   FILE *res = fdopen (fd, mode);
   if (! res)
-    error (EXIT_FAILURE, get_errno (), "fdopen");
+    error (EXIT_FAILURE, get_errno (),
+           // On a separate line to please the "unmarked_diagnostics"
+           // syntax-check.
+           "fdopen");
   return res;
 }
 

src/output.c

@@ -23,7 +23,6 @@
 
 #include <concat-filename.h>
 #include <configmake.h>
-#include <error.h>
 #include <filename.h>
 #include <get-errno.h>
 #include <quotearg.h>