use try_compile() instead of custom execute_process

The previous setup made a number of assumptions, e.g., on the
compiler executable name, which made the setup fail
unnecessarily in many cases.
This commit removes much of the custom code and resides to
CMake's own functionality.

Fixes bug #9 and bug #12.
Provide defaults for CINT{1,2} and NFINT{1,2} parameters
Merge branch 'master' of https://github.com/Unidata/netcdf-fortran
properly use GnuInstallDirs

Fixes bug #8.
Merge branch 'gnuinstalldirs' of https://github.com/nschloe/netcdf-fortran into nschloe-gnuinstalldirs
Merge branch 'try-comple' of https://github.com/nschloe/netcdf-fortran into nschloe-try-comple
Merge branch 'nschloe-try-comple'
Made a few fixes to get 'make distcheck' working.  Turned off texi file processing for the moment.
Ensuring CMakeExtras are included in the tarball generated by 'make dist'.
Generating Makefile in CmakeExtras directory.
Ensure autotool distribution contains CmakeLists.txt files.
Added missing file to EXTRA_DIST
Added a generic Doxyfile for generating documentation suitable for developers, not users.
Merge branch 'master' of https://github.com/Unidata/netcdf-fortran
Bumped version number for library.
Updated version number for library.
Corrected issues using SOVERSION with cmake.
Merge branch 'master' into ward-working