Don't require Qt GUI module

Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
---
diff -Nrup qextserialport-f83b4e7ca922e53.orig/qextserialport.pro qextserialport-f83b4e7ca922e53/qextserialport.pro
--- qextserialport-f83b4e7ca922e53.orig/qextserialport.pro	2012-10-17 09:13:53.000000000 +0200
+++ qextserialport-f83b4e7ca922e53/qextserialport.pro	2012-11-13 22:48:29.249431510 +0100
@@ -41,6 +41,8 @@ macx:qesp_mac_framework {
 
 win32|mac:!wince*:!win32-msvc:!macx-xcode:CONFIG += debug_and_release build_all
 
+!win32*:!wince*:QT -= gui
+
 #generate proper library name
 greaterThan(QT_MAJOR_VERSION, 4) {
     QESP_LIB_BASENAME = QtExtSerialPort