Remove /* foo.c */ comments

This was done by the following
        find . -name '*.[ch]' | /tmp/pl
where /tmp/pl is the following three-line script:
        print unless $. == 1 && m@/\* .*\.[ch] \*/@;
        close ARGV if eof; # Close file to reset $.

And then some hand-editing of other files.

Reviewed-by: Viktor Dukhovni <viktor@openssl.org>

engines/e_dasync_err.c

@@ -1,4 +1,3 @@
-/* e_dasync_err.c */
 /* ====================================================================
  * Copyright (c) 1999-2015 The OpenSSL Project.  All rights reserved.
  *