qtscript: Check for QtGui before building the examples

qsdbg and marshal examples need QtGui module. If QtGui is not installed
they fail to compile.

Change-Id: I1af6a8b39a0848c8208fe94a26ee57409dfd9b41
Reviewed-by: Vicente Olivert Riera <Vincent.Riera@imgtec.com>
Reviewed-by: Allan Sandfeld Jensen <allan.jensen@digia.com>
Bump MODULE_VERSION to 5.3.1

Change-Id: I52c832fc93ebde96fbc67ca72c709b794fcea9bd
Reviewed-by: Jędrzej Nowacki <jedrzej.nowacki@digia.com>
Fix compilation under precompiled headers: define _CRT_RAND_S

If the macro _CRT_RAND_S is defined, #include <stdlib.h> will define the
rand_s function. All was well before the precompiled headers because
wtf/config.h was always the first header included in WTF and it #defined
at the right place. With precompiled headers, stdlib.h got included from
qglobal.h before the #define took place.

This was a latent bug because the non-JSC parts of QtScript could have
included RandomNumberSeed.h and caused the error.

RandomNumberSeed.h(82) : error C3861: 'rand_s': identifier not found

Change-Id: I88b4b8670604b35ca694c02522324ac3083ed2b4
Reviewed-by: Sergio Ahumada <sahumada@blackberry.com>
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@digia.com>
Merge remote-tracking branch 'origin/stable' into dev

Conflicts:
	.qmake.conf

Change-Id: Ia3c3478a804b369b00aabb5739f409bd11dbb982