Fixed autogen.sh warnings on Debian 6 systems.

Signed-off-by: Chris Rempel <csrl@gmx.com>

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AUTHORS

@@ -10,6 +10,7 @@ Bob Beaty <rbeaty@peak6.com>
 Brian Buchanan <bwb@holo.org>
 Burak Arslan <burak-github@arskom.com.tr>
 Chia-liang Kao <clkao@clkao.org>
+Chris Rempel <csrl@gmx.com>
 Chris Wong <chris@chriswongstudio.com>
 Christian Gudrian <christian.gudrian@fluidon.com>
 Conrad D. Steenberg <conrad.steenberg@caltech.edu>

configure.in

@@ -6,7 +6,7 @@ AC_PREREQ(2.61)
 # the version.sh script. Hence, it should be updated there.
 # The version in git should reflect the *next* version planned.
 #
-AC_INIT([zeromq],[m4_esyscmd([./version.sh | tr -d '\n'])],[zeromq-dev@lists.zeromq.org])
+AC_INIT([zeromq],[m4_esyscmd_s([./version.sh])],[zeromq-dev@lists.zeromq.org])
 
 AC_CONFIG_AUX_DIR(config)
 AC_CONFIG_MACRO_DIR(config)