Add more useful exports to soffice's callgrind mode

Add more useful exports to soffice's callgrind mode

Moved from TDF wiki to avoid duplication.

These three stop us getting poor performance from unusual allocators:
unset MALLOC_CHECK_ MALLOC_PERTURB_ G_SLICE

If we wedge, at least we don't do it while grabbing the mouse:
export SAL_DISABLE_FLOATGRAB=1

Turns off recovery dialog, which can be a pain:
export OOO_DISABLE_RECOVERY=1

Turns off GL watchdog. It normally kills the application, if it
seems to hang in a GL block:
export SAL_DISABLE_GL_WATCHDOG=1

Change-Id: I4ec30d363280b727cd305a6a81ccb85849697159
Reviewed-on: https://gerrit.libreoffice.org/73773
Tested-by: Jenkins
Reviewed-by: Luboš Luňák <l.lunak@collabora.com>
Reviewed-by: Xisco Faulí <xiscofauli@libreoffice.org>