Move most of header check to autoconf.

As well as remove support for system doesn't have getrusage().
This will be resotred later.
Delete SIGNED and VOLATILE macros.
Remove configure.h and completely replaced by autoconf.
Move some library detection into autoconf.
Check local_options in autoconf.
Get rid of system_libs, library checking is in autoconf now.
Adding missing files.
Adding missing crypt.h check.
Use compile to check for local_options instead.
Correctly use iconv_open to detect libiconv.
Delete the old random detector warning code.
solve iconv problem on CYGWIN
solve posix_timer problem on CYGWIN
Merge pull request #96 from sunyc/master

Fully migrate to autoconf