Force -fPIE on ELF if Qt is built with reduced relocations

Force -fPIE on ELF if Qt is built with reduced relocations

Put in qconfig.h whether qt is compiled with reduced relocations.

When using -Bsymbolic-functions (enabled by default on Qt)
but not -fPIE, the comparison of the function pointers fail
because the addresses are different in Qt, and in the executable.

Hence we now enable -fPIE by default on qmake, and force a compilation
error when it is not enabled and built with reduced relocations.

Done-with: Sune Vuorela <sune@vuorela.dk>
Change-Id: Ib3fdba06fab6e8a93b75b4c6cf16cc973ab335db
Reviewed-by: Bradley T. Hughes <bradley.hughes@nokia.com>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>