Workaround compilation problems on gcc 4.6.0

As gcc 4.6.0 treats more warnings as errors, memcached compilation fails.
Solution took from original bug report for memcached.

slapos/profile/memcached.cfg

@@ -40,6 +40,8 @@ patches =
   ${memcached-strict-aliasing-patch:location}/${memcached-strict-aliasing-patch:filename}
   ${memcached-fix-array-subscript-is-above-array-bounds:location}/${memcached-fix-array-subscript-is-above-array-bounds:filename}
 patch-options = -p1
+# CFLAGS=-Wno-error=unused-but-set-variable allows to compile on gcc 4.6.0
+# http://code.google.com/p/memcached/issues/detail?id=199
 environment =
+    CFLAGS=-Wno-error=unused-but-set-variable
     LDFLAGS =-Wl,-rpath ${libevent:location}/lib
-