Link against official Qt first on macOS

In case there are multiple Qt installations, this will ensure the
application will be linked against the official Qt, which has
the default installation path in `~/Qt' and not Homebrew's Qt,
for example. This is done because of the Qt bug fixed in 5.10.

See also: mattanger#46,
https://bugreports.qt.io/browse/QTBUG-56814

qmake-auto

@@ -11,7 +11,7 @@ if [[ "$QMAKE" != "" ]]; then
 fi
 if [[ "$OSTYPE" == "darwin"* ]]; then
     # OSX: Look for qmake in standard install locations
-    QMAKE=`find /usr/local/opt/qt5/bin ~/Qt/*/clang_64/bin ~/Qt5*/*/clang_64/bin ~/Applications/Qt/*/clang_64/bin ~/Applications/Qt5*/*/clang_64/bin /Applications/Qt/*/clang_64/bin /Applications/Qt5*/*/clang_64/bin -name qmake -print -quit 2>/dev/null`
+    QMAKE=`find ~/Qt/*/clang_64/bin ~/Qt5*/*/clang_64/bin ~/Applications/Qt/*/clang_64/bin ~/Applications/Qt5*/*/clang_64/bin /Applications/Qt/*/clang_64/bin /Applications/Qt5*/*/clang_64/bin /usr/local/opt/qt5/bin -name qmake -print -quit 2>/dev/null`
     [[ $QMAKE == "" ]] && die
 else
     # Linux: Look for system-installed Qt5