Added QMAKESPEC to the list of unexported symbols

Building QT might fail if QMAKESPEC is defined.

Signed-off-by: Stephan Hoffmann <sho@relinux.de>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

Makefile

@@ -209,6 +209,7 @@ unexport CFLAGS
 unexport CXXFLAGS
 unexport GREP_OPTIONS
 unexport CONFIG_SITE
+unexport QMAKESPEC
 
 GNU_HOST_NAME:=$(shell support/gnuconfig/config.guess)