Fixed configure exiting with 0 exit code even on failure.

The return value from system() is an exit status (e.g. returned value
from waitpid) and needs to be shifted right by 8 bits to get an exit
code.

Change-Id: Ibbcc58491b27ef6d9d299427aeb78f57b41c92e2
Sanity-Review: Qt Sanity Bot <qt_sanity_bot@ovi.com>
Reviewed-by: João Abecasis <joao.abecasis@nokia.com>

configure

@@ -56,7 +56,7 @@ if (-e ".qmake.cache") {
     unlink ".qmake.cache";
 }
 my $ret = system_v("$relpath/qtbase/configure @ARGV");
-exit $ret unless ($ret == 0);
+exit ($ret>>8) unless ($ret == 0);
 if (! -e ".qmake.cache") {
     # Even though there was no error code, this file wasn't created
     # so configure didn't finish properly. This is probably because
@@ -71,4 +71,4 @@ print QMAKE_CACHE "include(\$\$PWD/qtbase/.qmake.cache)\n";
 close QMAKE_CACHE;
 
 $ret = system_v("$outpath/qtbase/bin/qmake $relpath/qt.pro");
-exit $ret;
+exit ($ret>>8);