maint: use space, not tab, in remote_protocol-structs

* src/Makefile.am (remote_protocol-structs): Flatten tabs.
* src/remote_protocol-structs: Likewise.  Also add a hint to emacs
to make it easier to keep spaces in the file.

src/Makefile.am

@@ -195,10 +195,14 @@ remote_protocol-structs:
 		-e '    $$p =~ s!\t*/\*.*?\*/!!sg;'			\
 		-e '    $$p =~ s!\s+\n!\n!sg;'				\
 		-e '    $$p =~ s!\s+$$!!;'				\
+		-e '    $$p =~ s!\t!        !g;'			\
 		-e '    print "$$p\n";'					\
 		-e '    $$n++;'						\
 		-e '  }'						\
 		-e '}'							\
+		-e 'BEGIN {'						\
+		-e '  print "/* -*- c -*- */\n";'			\
+		-e '}'							\
 		-e 'END {'						\
 		-e '  if ($$n < 300) {'					\
 		-e '    warn "WARNING: your pdwtags program is too old\n";' \