fixing small typo
Fix compilation under CentOS

I hope I didn't broke anything, but it works for me.
Mac OS X doesn't support uname -o. Use uname instead.

I break compatibility with Mac OS X again, that I don't have access
to. Result: Stuff break, and I have to fix it, so it will perhaps
work. At least, I hope it will work.
configure.ac: remove m4_esyscmd_s

m4_esyscmd_s is a macro only available in Autoconf 2.64, which despite
being released in 2009 is not available on a number of build targets for
the project (specifically CentOS/RHEL 6).

ca8e4c08a78 tries to remove the error produced with m4_pattern_allow,
but that just silences the sanity check.

Instead, replace m4_esyscmd_s with m4_esyscmd + manual removal of
newlines.
Merge remote-tracking branch 'upstream/master'