[xmlsec] build system changes

[Aleksey Sanin]

Hi, All!

I would like to make some changes to the current xmlsec build
system. Currently we have followng situation:

*nix, Mac, etc. (autogen/automake/autoconf):
    We build all possible xmlsec-<crypto> libraries but only
    one xmlsec  command line tool linked against "default"
    crypto library
    RPMs are build as follows:
         - xmlsec, xmlsec-devel: core xmlsec and default
         xmlsec-<crypto> libraries, command line tool linked
         against the default crypto libs. For my RPMs, default
         crypto means "openssl".
         - xmlsec-nss, xmlsec-nss-devel: libs for xmlsec-nss,
         no executable 

Windows:
    We build libraries and executable for the default crypto only.

I would like to change these and *aways* build all the xmlsec-<crypto>
libraries and xmlsec command line tools linked with each of
xmlsec-<crypto> libraries:

*nix, Mac, etc. (autogen/automake/autoconf):
    As before build all libraries (of course, user can disable
    some libraries from ./configure script). Build xmlsec1-openssl,
    xmlsec1-nss, xmlsec1-gnutls, etc. command line tools and
    later make a symbolic link "xmlsec1"-->"xmlsec1-<default crypto>".
    Probably there would be an option "--default-crypto" for
    ./configure script too.
    Also, RPMs would now have following structure:
        - xmlsec, xmlsec-devel: core xmlsec libraries, no executables
        - xmlsec-openssl, xmlsec-openssl-devel: openssl libs and
        executable
        - xmlsec-nss, xmlsec-nss-devel: nss libs and executable
 
Windows:
    Build libraries and command line tools for all crypto libraries listed
    in comma separated list in option "crypto" for the configure.js script.
    After that, copy the "xmlsec-<default-crypto>.exe" to "xmlsec.exe"
    where <default-crypto> is the first item in the "crypto" list (do we 
need
    a separate "default-crypto" option?).

I would appreciate if John, Igor and everyone else interested can review
this plan and send your comments/suggestions. I am going to make these
changes next week on MS Crypto branch so we would have some bake time.

Thanks,
Aleksey