Library GMP is not yet ready for GCC 4.9, as described at bottom of page

http://gcc.gnu.org/gcc-4.9/porting_to.html

See extract below:

The <cstddef> header was updated for C++11 support and this breaks some
libraries which misuse macros meant for internal use by GCC only. For
instance with GMP versions up to 5.1.3, you may see:

/usr/include/c++/4.9.0/cstddef:51:11: error: ‘::max_align_t’ has not been declared
   using ::max_align_t;
           ^

Another possible error is:

someheader.h:99:13: error: ‘ptrdiff_t’ does not name a type

A workaround until libraries get updated is to include <cstddef> or
<stddef.h> before any headers from that library.
Ubuntu 14.04 compilation help update:

- add patch from Hans Erik van Elburg posted on mailing-list on
  9-May-2014
- add also some documentation in README files
Hardy, Karmic, Oneiric are obsolete Ubuntu releases.
See http://en.wikipedia.org/wiki/List_of_Ubuntu_releases#Table_of_versions
Merge pull request #286 from thdox/fix-gcc-4.9

Fix compiling with GCC 4.9

Thanks Thierry, nice to see you back.
Merge pull request #287 from thdox/fix-for-ubuntu-14.04

Fix for ubuntu 14.04