I don't have time today to look into this further, but it looks like it is because the code that checks the CFLAGS is trying to use the previous CFLAG checking attempt. Below is from my FreeBSD box that is having the same problem as the OS X buildbot: it doesn't actually try -Warray-bounds until it gets to the next check (-Wformat-security), then you see -Warray-bounds in the gcc line. This is from config.log and it makes the GTK+ check program fail using -Warray-bounds, which my gcc doesn't support.
configure:22403: checking whether we can add -Warray-bounds to CFLAGS
configure:22419: gcc -c -g -O2 -Wall -W -Wextra -Wdeclaration-after-statement -Wendif-labels -Wpointer-arith -Wno-pointer-sign conftest.c >&5
configure:22419: $? = 0
configure:22421: result: yes
configure:22490: checking whether we can add -Warray-bounds to CXXFLAGS
configure:22512: g++ -c -g -O2 -Wall -W -Wextra -Wendif-labels -Wpointer-arith conftest.cpp >&5
configure:22512: $? = 0
configure:22514: result: yes
configure:22608: checking whether we can add -Wformat-security to CFLAGS
configure:22624: gcc -c -g -O2 -Wall -W -Wextra -Wdeclaration-after-statement -Wendif-labels -Wpointer-arith -Wno-pointer-sign -Warray-bounds conftest.c >&5
cc1: error: unrecognized command line option "-Warray-bounds"
configure:22624: $? = 1
> Date: Tue, 2 Jul 2013 16:36:51 -0700
> From: buildbot-no-reply@xxxxxxxxxxxxx
> To: wireshark-commits@xxxxxxxxxxxxx
> Subject: [Wireshark-commits] buildbot failure in Wireshark (development) on OSX-10.5-x86
>
> The Buildbot has detected a new failure on builder OSX-10.5-x86 while building Wireshark (development).
> Full details are available at:
> http://buildbot.wireshark.org/trunk/builders/OSX-10.5-x86/builds/6046
>
> Buildbot URL: http://buildbot.wireshark.org/trunk/
>
> Buildslave for this Build: osx-10.5-x86
>
> Build Reason: scheduler
> Build Source Stamp: 50330
> Blamelist: sfisher
>
> BUILD FAILED: failed configure
>
> sincerely,
> -The Buildbot
>
>
>
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