autogen.sh: use glibtoolize when available

libtoolize is called glibtoolize on osx.

Signed-off-by: Noah Watkins <noahwatkins@gmail.com>
byteorder: use platform specific files

Signed-off-by: Noah Watkins <noahwatkins@gmail.com>
byteorder: add darwin platform specific version

Signed-off-by: Noah Watkins <noahwatkins@gmail.com>
conf: use ac_config_links to select platform files

Uses the detected platform to link

  include/platform

to a specific platform (e.g. include/freebsd).

Signed-off-by: Noah Watkins <noahwatkins@gmail.com>
assert: use portable m4 to test for static_cast

Signed-off-by: Noah Watkins <noahwatkins@gmail.com>
assert: choose function-name var per platform

Selects __PRETTY_FUNCTION__ or __func__. Linux assumes GNU, and chooses
__PRETTY_FUNCTION__ if gcc/g++ versions are favorable.

Signed-off-by: Noah Watkins <noahwatkins@gmail.com>
m4: fix ax_c_var_func nested function

AC_TRY_COMPILE will wrap the test in main{}, and then GCC will complain
about nested functions. Just use the original main{} body.

Signed-off-by: Noah Watkins <noahwatkins@gmail.com>