qt4: Bring in improvements from meta-openembedded

Differences from meta-openembedded version:
* SRC_URI and S now come from qt-${PV}.inc since these are version specific
* Source checksums are also now in qt-${PV}.inc
* Remove do_compile as this is handled in qt-${PV}.inc
* Move contents of do_install_append from qt-${PV}.inc to do_install in
  qt4.inc as this is the same for 4.6.3 and 4.7.1 and will get in the way of
  do_install_append in qt-embedded.inc.
* Don't enable PostgreSQL, MySQL or SQLite 2.x plugins as we don't currently
  have recipes for these DBMSs in Poky. These can be re-enabled easily when
  or if we do.
* Use INC_PR in qt4-x11-free_4.6.3.bb
* Don't always specify -embedded config option in qt4.inc
* Don't add qte.sh to SRC_URI in qt-4.6.3.inc (this is embedded-specific)

Differences from what we have currently in Poky (plus the above):
* Set DESCRIPTION based on embedded/X11
* Move out arch-specific settings to qt4-arch.inc
* Add qt4x11.bbclass which can be inherited by application recipes to select
  the X11 version (this makes more sense once the embedded version is added).
* Update HOMEPAGE

Signed-off-by: Paul Eggleton <paul.eggleton@linux.intel.com>

meta/classes/qt4x11.bbclass

@@ -0,0 +1,9 @@
+DEPENDS_prepend = "${@["qt4-x11-free ", ""][(bb.data.getVar('PN', d, 1)[:12] == 'qt4-x11-free')]}"
+
+inherit qmake2
+
+QT_DIR_NAME = "qt4"
+QT_LIBINFIX = ""
+
+# Qt4 uses atomic instructions not supported in thumb mode
+ARM_INSTRUCTION_SET = "arm"