Fix for bug #78048.

Problem was that the malloc-replacing tools (memcheck, addrcheck, massif,
helgrind) would assert if a too-big malloc was attempted.  Now they return 0 to
the client.  I also cleaned up the code handling heap-block-metadata in Massif
and Addrcheck/Memcheck a little.

This exposed a nasty bug in VG_(client_alloc)() which wasn't checking if
find_map_space() was succeeding before attempting an mmap().  Before I added
the check, very big mallocs (eg 2GB) for Addrcheck were overwriting the client
space at address 0 and causing crashes.

Added a regtest to all the affected skins for this.


git-svn-id: svn://svn.valgrind.org/valgrind/trunk@2462 a5019735-40e9-0310-863c-91ae7b9d1cf9
22 files changed