Explicitly set OS2Vendor to 'PfEd'

That's the default value that FontForge uses.  I'd like to change it,
but fontconfig makes it available to applications as "foundry" and I
somehow ended up with Emacs recording that in its configuration.  So if
I'm going to make that change I think it should go with a major version
bump.

But at least I can make sure it doesn't change unexpectedly and give
myself somewhere to make the change when it comes.

bedstead.c

@@ -2838,6 +2838,7 @@ main(int argc, char **argv)
 	printf("TTFWeight: %d\n", weight->ttfweight);
 	printf("TTFWidth: %d\n", width->ttfwidth);
 	dopanose();
+	printf("OS2Vendor: 'PfEd'\n");
 	printf("OS2FamilyClass: %d\n", 0x080a);
 	printf("LayerCount: 2\n");
 	printf("Layer: 0 0 \"Back\" 1\n");