Add a generic pragma-handling infrastructure

Add infrastructure for handling %pragmas with a variety of namespaces,
etc., etc...

Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

output/codeview.c

@@ -71,6 +71,7 @@ const struct dfmt df_cv8 = {
     cv8_typevalue,              /* .debug_typevalue */
     cv8_output,                 /* .debug_output */
     cv8_cleanup,                /* .cleanup */
+    NULL                        /* pragma list */
 };
 
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