rtcd.pl: tolerate mixed output line endings

strip the default eol from the config header line, then a '\r' if there
is one. this can occur if cmake used to output the header uses windows
eol, but the perl used expects newlines for instance.

Change-Id: I687415878b1a04fd94b12d7b3d3066f448630607

build/make/rtcd.pl

@@ -51,6 +51,7 @@ my %config = ();
 while (<CONFIG_FILE>) {
   next if !/^(?:CONFIG_|HAVE_)/;
   chomp;
+  s/\r$//;
   my @pair = split /=/;
   $config{$pair[0]} = $pair[1];
 }