squid: bump to version 3.4.3

And exclude for avr32 since the toolchain is too old, fixes:
http://autobuild.buildroot.net/results/c6a/c6a686885a6c845b527c58c3f2075f82bcf120e2/



Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>