Silence warning from clang

The original intent was most likely to memset() the entire MD5Context to
zero at the end of MD5Final(), which we do now.

In file included from tools/qcryptographichash.cpp:49:
...qtbase/src/corelib/../../include/QtCore/../../src/corelib/tools/../../3rdparty/md5/md5.cpp:139:24:
warning:
      argument to 'sizeof' in 'memset' call is the same expression as
the
      destination; did you mean to dereference it? [-Wsizeof-pointer-
        memset(ctx, 0, sizeof(ctx));    /* In case it's sensitive */
               ~~~            ^~~

Change-Id: I793c6f0944b89c0e4c5f9253cdb1071175c17152
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
(cherry-picked from qtbase commit 2bce4627e63947a3ed55009aeb8ff38974e444d3)
Reviewed-by: Olivier Goffart <ogoffart@woboq.com>
Rename qAbs Function for timeval

This decouples it from qAbs which is declared as a constexpr under
certain compilation flags and enables for qtbase to be compiled with
GCC 4.8

Change-Id: I78e02256ffc8b460ca74ae5241e77dfac4e09ba9
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
(cherry-picked from qtbase commit d9ff510f02bba63dabe7a081a68296056a89ae4c)
Reviewed-by: Olivier Goffart <ogoffart@woboq.com>