fix build with no built-in image handlers

the handlers' .pri files added $$PWD to INCLUDEPATH to make the files
self-contained when used externally, but this polluted the include path
of the gui module itself, thus hiding incorrect use of QPA includes.

Task-number: QTBUG-47400
Change-Id: I576469a71e8ded0b409d62687999c0fa884613f9
Reviewed-by: Joerg Bornemann <joerg.bornemann@theqtcompany.com>

src/gui/image/qgifhandler.pri

@@ -1,4 +1,3 @@
 # common to plugin and built-in forms
-INCLUDEPATH *= $$PWD
 HEADERS += $$PWD/qgifhandler_p.h
 SOURCES += $$PWD/qgifhandler.cpp

src/gui/image/qjpeghandler.pri

@@ -1,5 +1,4 @@
 # common to plugin and built-in forms
-INCLUDEPATH *= $$PWD
 HEADERS += $$PWD/qjpeghandler_p.h
 SOURCES += $$PWD/qjpeghandler.cpp
 contains(QT_CONFIG, system-jpeg) {

src/gui/image/qpnghandler.pri

@@ -1,4 +1,3 @@
-INCLUDEPATH *= $$PWD
 HEADERS += $$PWD/qpnghandler_p.h
 SOURCES += $$PWD/qpnghandler.cpp
 contains(QT_CONFIG, system-png) {

src/gui/painting/qbrush.cpp

@@ -35,7 +35,7 @@
 #include "qpixmap.h"
 #include "qbitmap.h"
 #include "qpixmapcache.h"
-#include "qplatformpixmap.h"
+#include <qpa/qplatformpixmap.h>
 #include "qdatastream.h"
 #include "qvariant.h"
 #include "qline.h"

src/plugins/imageformats/gif/gif.pro

@@ -5,6 +5,7 @@ PLUGIN_CLASS_NAME = QGifPlugin
 load(qt_plugin)
 
 include(../../../gui/image/qgifhandler.pri)
+INCLUDEPATH += ../../../gui/image
 SOURCES += $$PWD/main.cpp
 HEADERS += $$PWD/main.h
 OTHER_FILES += gif.json

src/plugins/imageformats/jpeg/jpeg.pro

@@ -9,6 +9,7 @@ QT += core-private
 QTDIR_build:REQUIRES = "!contains(QT_CONFIG, no-jpeg)"
 
 include(../../../gui/image/qjpeghandler.pri)
+INCLUDEPATH += ../../../gui/image
 SOURCES += main.cpp
 HEADERS += main.h
 OTHER_FILES += jpeg.json