Infrastructure cleanup part 2. valgrind side changes.
Replace Iex_Mux0X with Iex_ITE (if-then-else).
Companion patch to VEX r2668.


git-svn-id: svn://svn.valgrind.org/valgrind/trunk@13273 a5019735-40e9-0310-863c-91ae7b9d1cf9
Fix a buffer overflow in VG_(assert_fail).
Patch by Matthias Schwarzott (zzam@gentoo.org) with some minor mods.
Fixes BZ 313811


git-svn-id: svn://svn.valgrind.org/valgrind/trunk@13274 a5019735-40e9-0310-863c-91ae7b9d1cf9