Doc: Replaced the HTTPS links with HTTP

The HTTPS links fail in Qt Assistant on Windows as the
qt installation package includes qt libraries that are
built without SSL support for legal reasons.

Task-number: QTBUG-31073
Change-Id: I86909abadb1e8164749d924cc53ee05aa57f8f31
Reviewed-by: Jerome Pasion <jerome.pasion@digia.com>
Reviewed-by: Karsten Heimrich <karsten.heimrich@digia.com>

src/widgets/kernel/qformlayout.cpp

@@ -1022,7 +1022,7 @@ QStyle* QFormLayoutPrivate::getStyle() const
     \li \b{Adherence to the different platform's look and feel guidelines.}
 
         For example, the
-        \l{https://developer.apple.com/library/mac/#documentation/UserExperience/Conceptual/AppleHIGuidelines/Intro/Intro.html}{Mac OS X Aqua} and KDE guidelines specify that the
+        \l{http://developer.apple.com/library/mac/#documentation/UserExperience/Conceptual/AppleHIGuidelines/Intro/Intro.html}{Mac OS X Aqua} and KDE guidelines specify that the
         labels should be right-aligned, whereas Windows and GNOME
         applications normally use left-alignment.
 
@@ -1065,7 +1065,7 @@ QStyle* QFormLayoutPrivate::getStyle() const
            corresponds to what we would get using a two-column
            QGridLayout.)
         \li Style based on the
-           \l{https://developer.apple.com/library/mac/#documentation/UserExperience/Conceptual/AppleHIGuidelines/Intro/Intro.html}{Mac OS X Aqua} guidelines. Labels are right-aligned,
+           \l{http://developer.apple.com/library/mac/#documentation/UserExperience/Conceptual/AppleHIGuidelines/Intro/Intro.html}{Mac OS X Aqua} guidelines. Labels are right-aligned,
            the fields don't grow beyond their size hint, and the
            form is horizontally centered.
         \li Recommended style for