mem: Add DRAM device size and check against config

This patch adds the size of the DRAM device to the DRAM config. It
also compares the actual DRAM size (calculated using information from
the config) to the size defined in the system. If these two values do
not match gem5 will print a warning. In order to do correct DRAM
research the size of the memory defined in the system should match the
size of the DRAM in the config. The timing and current parameters
found in the DRAM configs are defined for a DRAM device with a
specific size and would differ for another device with a different
size.
ext: Bump DRAMPower to avoid compilation issues

This patch bumps DRAMPower to commit
19433a6897ede4bbb19b06694faa8589b5a6569a which contains a small fix
for clang, and a work-around for LTO with gcc 4.6.
base: Fix for stats node on gcc < 4.6.3

This patch adds an explicit function to get the underlying node as gcc
4.6.1 and 4.6.2 have issues otherwise.
mem: Fix DRAM activationlLimit bug

Ensure that we do the proper event scheduling also when the activation
limit is disabled.
misc: Use gmtime for conversion to UTC to avoid getenv/setenv

This patch changes how we turn time into UTC. Previously we
manipulated the TZ environment variable, but this has issues as the
strings that are manipulated could be tainted (see e.g. CERT
ENV34-C). Now we simply rely on the built-in gmtime function and avoid
touching getenv/setenv all together.
x86: Fixes to avoid LTO warnings

This patch fixes a few minor issues that caused link-time warnings
when using LTO, mainly for x86. The most important change is how the
syscall array is created. Previously gcc and clang would complain that
the declaration and definition types did not match. The organisation
is now changed to match how it is done for ARM, moving the code that
was previously in syscalls.cc into process.cc, and having a class
variable pointing to the static array.

With these changes, there are no longer any warnings using gcc 4.6.3
with LTO.