Accept "owner" as an alias to "user" %verify attribute (RhBug:838657)

- Both Maximum RPM and the newer RPM Guide incorrectly list "owner"
  as a valid %verify() attribute, whereas rpm has used "user"
  for as long as the code has been present (since 1996). Since
  adding the alias is so trivial, and certainly easier than changing
  published books... meh.

build/files.c

@@ -278,6 +278,7 @@ static VFA_t const verifyAttrs[] = {
     { "size",		RPMVERIFY_FILESIZE },
     { "link",		RPMVERIFY_LINKTO },
     { "user",		RPMVERIFY_USER },
+    { "owner",		RPMVERIFY_USER },
     { "group",		RPMVERIFY_GROUP },
     { "mtime",		RPMVERIFY_MTIME },
     { "mode",		RPMVERIFY_MODE },