[V8] uclibc: __GLIBC__ might be defined on uclibc builds

[V8] uclibc: __GLIBC__ might be defined on uclibc builds

Uclibc defines __GLIBC__ becuase it is compatible in some ways with,
but it does not provide execinfo. Uclibc provides a define to disable
defining __GLIBC__ but Qt does not build with that right now. Check
for GLIBC and !UCLIBC here.

Change-Id: I582a16d16151f30c696ed0e9d185e2706599abe7
Sanity-Review: Qt Sanity Bot <qt_sanity_bot@ovi.com>
Reviewed-by: Kent Hansen <kent.hansen@nokia.com>
Reviewed-by: Simon Hausmann <simon.hausmann@nokia.com>