ARM: do not use the clang integrated assembler in some cases.

The integrated assembler of clang does not understand some/all of the
ARM macro assembler syntax used in pixman-arm-neon-asm.S. By default,
this integrated assembler is used when using the "clang" command as a
driver. This patch turns off the integrated assembler of clang for that
file.

Change-Id: Ic06801266b5a4b097ca835d815bcc5d5fc672946
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@digia.com>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Add tests for assignment operator

Change-Id: I3265cb75c4d785faaf1efc183d8c1293dfff9165
Reviewed-by: Jędrzej Nowacki <jedrzej.nowacki@digia.com>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Tidy up and expand QSharedPointer documentation.

Also adds the 5.4.0 changes file.

Change-Id: I10967ca179b91229e7d1ee0fc666bbd8dbe54425
Reviewed-by: Jerome Pasion <jerome.pasion@digia.com>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>