Do not unconditionally use pkg-config in .pro files

Using the first pkg-config in PATH is prone to errors when
cross compiling.  This is a known issue, and `configure' already
avoids using pkg-config for cross compiling (unless -force-pkg-config is
used).  However, there was previously no way for a .pro file to test
whether or not the user had passed -force-pkg-config.

Let !contains(QT_CONFIG, no-pkg-config) be used to test whether or not it
is safe to run pkg-config.

(cherry picked from commit 53794d94994cb3149581b1a91762dfa2d6defac0)

Change-Id: I53794d94994cb3149581b1a91762dfa2d6defac0
Reviewed-by: Sergio Ahumada <sergio.ahumada@nokia.com>
Reviewed-on: http://codereview.qt-project.org/6488
Reviewed-by: Rohan McGovern <rohan.mcgovern@nokia.com>

0 files changed, 0 insertions, 0 deletions