mkqt5bld: Use shlex.split(s) instead of s.split(' ') for configure arguments

This solves a problem when you pass arguments to configure like

  configure.bat -openssl-linked OPENSSL_LIB="-lssl -lcrypto"

since s.split(' ') will create

  ['configure.bat', '-openssl-linked', 'OPENSSL_LIB="-lssl', '-lcrypto"']

which then will fail as '-lcrypto' is not recognized as a valid argument
for configure.exe

Doing shlex.split(s) will create

  ['configure.bat', '-openssl-linked', 'OPENSSL_LIB=-lssl -lcrypto']

instead, which is actually the right thing to do.

Change-Id: I187f71814e8401ac881c2643c1f09d3b7596bfdd
Reviewed-by: Iikka Eklund <iikka.eklund@digia.com>