qtdeclarative: add upstream patch to fix QtQml crash with GCC 6

Signed-off-by: Jonathan Liu <net147@gmail.com>
Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>

recipes-qt/qt5/qtdeclarative/0003-Workaround-crashes-in-QtQml-code-related-to-dead-sto.patch

@@ -0,0 +1,44 @@
+From fcc2c95421710f98c7b2dec73e2c8b0d9164bc9b Mon Sep 17 00:00:00 2001
+From: Jonathan Liu <net147@gmail.com>
+Date: Wed, 24 Aug 2016 11:18:37 +1000
+Subject: [PATCH] Workaround crashes in QtQml code related to dead-store
+ elimination
+
+When compiled in release mode with GCC 6, QtQml may crash.
+This is because the C++ compiler is more aggressive about dead-store
+elimination in situations where a memory store to a location precedes
+the construction of an object at that memory location.
+
+The QV4::MemoryManager::allocate{Managed,Object} functions allocate
+memory and write to it before the caller does a placement new to
+construct an object in the same memory. The compiler considers these
+writes before the constructor as "dead stores" and eliminates them.
+
+The -fno-lifetime-dse compiler flag is added to disable this more
+aggressive dead-store eliminiation optimization.
+
+This is a temporary workaround until a proper solution is found.
+
+Upstream-Status: Accepted
+
+Task-number: QTBUG-55482
+Change-Id: I7dbae6e9e613e53ce5fb25957c449bc6657803b5
+Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
+Signed-off-by: Jonathan Liu <net147@gmail.com>
+---
+ src/qml/qml.pro | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git a/src/qml/qml.pro b/src/qml/qml.pro
+index f4862a1..651afa6 100644
+--- a/src/qml/qml.pro
++++ b/src/qml/qml.pro
+@@ -18,7 +18,7 @@ exists("qqml_enable_gcov") {
+ 
+ greaterThan(QT_GCC_MAJOR_VERSION, 5) {
+     # Our code is bad. Temporary workaround.
+-    QMAKE_CXXFLAGS += -fno-delete-null-pointer-checks
++    QMAKE_CXXFLAGS += -fno-delete-null-pointer-checks -fno-lifetime-dse
+ }
+ 
+ QMAKE_DOCS = $$PWD/doc/qtqml.qdocconf

recipes-qt/qt5/qtdeclarative_git.bb

@@ -16,6 +16,7 @@ DEPENDS += "qtbase"
 SRC_URI += " \
     file://0001-qmltestexample-fix-link.patch \
     file://0002-qquickviewcomparison-fix-QCoreApplication-has-not-be.patch \
+    file://0003-Workaround-crashes-in-QtQml-code-related-to-dead-sto.patch \
 "
 
 EXTRA_OEMAKE += "QMAKE_SYNCQT=${STAGING_BINDIR_NATIVE}${QT_DIR_NAME}/syncqt"