Prefer QSKIP to QTEST_NOOP_MAIN.

Prefer QSKIP to QTEST_NOOP_MAIN.

There is no way for a .pro file to know if QProcess is in the Qt build,
so the QProcess autotest cannot be omitted from the build if QProcess is
not available.  Because of this limitation, the test was using
QTEST_NOOP_MAIN when QProcess was not available, making the test appear
to pass.  This commit changes QTEST_NOOP_MAIN to QSKIP, so that the user
receives a clear indication that the test isn't testing anything when
QProcess is not available.

Change-Id: I79f667b17ff98dfc47eb61fb977365abef8883fb
Reviewed-by: Rohan McGovern <rohan.mcgovern@nokia.com>