Be more robust when reading the library version number from pkg-config

Ignore everything that after the initial period separated numbers.

Change-Id: I376b154ff0ab6e3877223ec1383ed4708ecd2164
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@theqtcompany.com>
Reviewed-by: Lars Knoll <lars.knoll@qt.io>

mkspecs/features/qt_configure.prf

@@ -493,6 +493,7 @@ defineTest(qtConfLibrary_pkgConfig) {
     eval(includes = $$includes)
     includes ~= s/^-I//g
     $${1}.includedir = "$$val_escape(includes)"
+    version ~= s/[^0-9.].*$//
     $${1}.version = $$first(version)
     export($${1}.libs)
     export($${1}.cflags)