This is update for configure, build and install of vector math library.

This is update for configure, build and install of vector math library.
Installation of libm.so as linker script only in case of libmvec.so build.

2015-05-14  Andrew Senkevich  <andrew.n.senkevich@gmail.com>

    * Makeconfig (rpath-dirs, all-subdirs): Added mathvec folder.
    (libmvec): New variable.
    * configure.ac: Added option for mathvec build.
    * configure: Regenerated.
    * mathvec/Depend: New file.
    * mathvec/Makefile: New file.
    * shlib-versions: Added libmvec.
    * math/Makefile: Added rule for libm.so installation.