Fix QString::toUcs4 returning invalid data when encountering stray surrogates

Code units 0xD800 .. 0xDFFF are not UCS-4, so we can't happily return them.
Instead, if we encounter a stray surrogate, replace it with 0xFFFD, which
is what Unicode recommends anyhow.

References:

§3.9 Unicode Encoding Forms

    D76: Unicode scalar value: Any Unicode code point except high-surrogate
    and low surrogate code points.

    As a result of this definition, the set of Unicode scalar values consists
    of the ranges 0 to D7FF_16 and E000_16 to 10FFFF_16, inclusive.

    [...]

    UTF-32 encoding form: The Unicode encoding form that assigns each Unicode
    scalar value to a single unsigned 32-bit code unit with the same numeric
    value as the Unicode scalar value.

§ C.2 Encoding Forms in ISO/IEC 10646

    UCS-4. UCS-4 stands for “Universal Character Set coded in 4 octets.” It is
    now treated simply as a synonym for UTF-32, and is considered the canonical
    form for representation of characters in 10646.

§ 3.9 Unicode Encoding Forms (Best Practices for Using U+FFFD)
and
§ 5.22 Best Practice for U+FFFD Substitution

    Whenever an unconvertible offset is reached during conversion of a code
    unit sequence:

    1. The maximal subpart at that offset should be replaced by a single
    U+FFFD.

    2. The conversion should proceed at the offset immediately after the
    maximal subpart.

    [...]

    Whenever an unconvertible offset is reached during conversion of a code
    unit sequence to Unicode:

    1. Find the longest code unit sequence that is the initial subsequence of
    some sequence that could be converted. If there is such a sequence, replace
    it with a single U+FFFD; otherwise replace a single code unit with a single
    U+FFFD.

    2. The conversion should proceed at the offset immediately after the
    subsequence which has been replaced.

[ChangeLog][QtCore][QString] QString::toUcs4 now does not return invalid
UCS-4 code units belonging to the surrogate range (U+D800 to U+DFFF)
when the QString contains malformed UTF-16 data. Instead, U+FFFD
is returned in place of the malformed subsequence.

Change-Id: I19d7af03e749fea680fd5d9635439bc9d56558a9
Reviewed-by: Lars Knoll <lars.knoll@digia.com>
Reviewed-by: Konstantin Ritt <ritt.ks@gmail.com>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
QUtfCodec: don't encode invalid UCS-4 codepoints

The code didn't check for malformed surrogate pairs. That means that

- high surrogates followed by *anything* were decoded as they formed
  a valid surrogate pair;
- stray low surrogates were returned as-is.

We can't return surrogate values in UCS-4, so properly detect these
cases and return U+FFFD instead.

[ChangeLog][QtCore][QTextCodec] Encoding a QString in UTF-32 will now
replace malformed UTF-16 subsequences in the string with the Unicode
replacement character (U+FFFD).

Change-Id: I5cd771d6aa21ffeff4dd9d9e5a7961cf692dc457
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Reviewed-by: Konstantin Ritt <ritt.ks@gmail.com>
qmake WinRT: Default to x86 for lib path

If VCPROJ_ARCH is not recognized or unset, make "arch" default to x86,
or link won't find the libs.

Change-Id: If2cbda37a80c0fa43e1464775c036cebf10f931a
Reviewed-by: Oliver Wolff <oliver.wolff@digia.com>
Reviewed-by: Joerg Bornemann <joerg.bornemann@digia.com>
WinRT: Use correct architecture values in manifests and vs

Using the same architecture value in VC Project and manifest
files only makes sense for x64. Instead of doing magic we
just set the correct values inside the mkspecs. VCPROJ_ARCH
is used for Visual Studio, while the manifests use
WINRT_MANIFEST.architecture.

WINRT_MANIFEST.architecture was added to x64 mkspecs for
consistency and phone mkspecs do not use WINRT_MANIFEST.architecture
so it does not have to be set there.

Change-Id: I009473104875b4add8c0530dc6f51177919e997b
Reviewed-by: Andrew Knight <andrew.knight@digia.com>
Optimize stringToCMap() usage

CMAP guarantees there is 1:1 mapping between the Unicode code points
array and the glyph indexes array, which means the QString length
always greater than or equal to a sufficient glyph indexes array length.

Simply add some asserts and improve the memory consumption
and the performance where possible.

Change-Id: I0bc8cdba5f86c1c0ba9e79c8d5f96cbe56ec463e
Reviewed-by: Lars Knoll <lars.knoll@digia.com>
glxconvenience: Add a QT_XCB_FORCE_SOFTWARE_OPENGL environment variable.

The QT_XCB_FORCE_SOFTWARE_OPENGL environment variable is equivalent to
LIBGL_ALWAYS_SOFTWARE for Qt 5 applications only. This is most useful
with drivers that only support OpenGL 1. We need OpenGL 2, but the user
probably doesn't want LIBGL_ALWAYS_SOFTWARE in OpenGL 1 apps.

Together with
http://pkgs.fedoraproject.org/cgit/qt5-qtbase.git/tree/10-qt5-check-opengl2.sh
which goes into /etc/X11/xinit/xinitrc.d, it makes QML 2 just work on
old hardware that supports only OpenGL 1.x in hardware. The scriptlet
checks the glxinfo output for the OpenGL version and sets
QT_XCB_FORCE_SOFTWARE_OPENGL if the major version is < 2. (The scriptlet
requires xorg-x11-xinit and glx-utils.)

Tested on a Radeon 9200 SE (RV280) that supports only OpenGL 1.3 in
hardware.

Change-Id: Ief80d283820d6336052b8f390a0030ba9b687492
Reviewed-by: Jørgen Lind <jorgen.lind@digia.com>