Do not require SSE2 on i686

See https://bugzilla.redhat.com/show_bug.cgi?id=1244196#c22 for the
history of the patch. Compared to the last revision there (v5):
* I fixed WebGLImageConversion.cpp to not assume SSE2 on x86.
  Unfortunately, it would be really hard to make runtime detection work
  there, because it uses intrinsics in inline templates, and GCC only
  supports intrinsics when building the whole code for the vector
  instruction set. So I had to turn off that SSE2 code entirely when
  __SSE2__ is not defined at compile time.
* I fixed webrtc to check for SSE2 at runtime (using the runtime
  checking code that webrtc already has and uses in several places)
  before attempting to use OpenMAX on x86. OpenMAX requires SSE2.
  So we just fall back to the Ooura implementation of FFTs when needed.
TODO: build V8 shared and twice (once for x87, once for SSE2)

qt5-qtwebengine.spec

@@ -24,7 +24,7 @@
 Summary: Qt5 - QtWebEngine components
 Name:    qt5-qtwebengine
 Version: 5.6.0
-Release: 0.13.beta%{?dist}
+Release: 0.13.beta.nosse2.1%{?dist}
 
 # See LICENSE.GPL LICENSE.LGPL LGPL_EXCEPTION.txt, for details
 # See also http://qt-project.org/doc/qt-5.0/qtdoc/licensing.html
@@ -64,6 +64,12 @@ Patch6:  qtwebengine-opensource-src-5.6.0-beta-system-icu-utf.patch
 # fix the NSS/BoringSSL "chimera build" to call EnsureNSSHttpIOInit
 # backport of https://codereview.chromium.org/1385473003
 Patch7:  qtwebengine-opensource-src-5.6.0-beta-chimera-nss-init.patch
+# do not require SSE2 on i686
+# cumulative revert of upstream reviews 187423002, 308003004, 511773002 (parts
+# relevant to QtWebEngine only), 516543004, 1152053004 and 1161853008, along
+# with some custom fixes and improvements
+# TODO: build V8 shared and twice (once for x87, once for SSE2)
+Patch8:  qtwebengine-opensource-src-5.6.0-beta-no-sse2.patch
 
 # the architectures theoretically supported by the version of V8 used (#1298011)
 # You may need some minor patching to build on one of the secondary
@@ -284,6 +290,7 @@ BuildArch: noarch
 %patch5 -p1 -b .system-nspr-prtime
 %patch6 -p1 -b .system-icu-utf
 %patch7 -p1 -b .chimera-nss-init
+%patch8 -p1 -b .no-sse2
 
 %build
 export STRIP=strip
@@ -353,6 +360,9 @@ popd
 
 
 %changelog
+* Sat Jan 16 2016 Kevin Kofler <Kevin@tigcc.ticalc.org> - 5.6.0-0.13.beta.nosse2.1
+- Do not require SSE2 on i686
+
 * Thu Jan 14 2016 Kevin Kofler <Kevin@tigcc.ticalc.org> - 5.6.0-0.13.beta
 - Drop nss321 backport (and the related nss-headers patch), it did not help
 - Do an NSS/BoringSSL "chimera build" as will be the default in Chromium 47