Noticed this when looking at swizzles.  It's at least better structure,
removing hard-to-see early returns, which might be contributing to bugs.

Add support for es extension GL_EXT_blend_func_extended

Add support for extension GL_EXT_shader_implicit_conversions

* Introduces builtin variables gl_SecondaryFragColorEXT and gl_SecondaryFragDataEXT
* Introduces builtin constant gl_MaxDualSourceDrawBuffersEXT
* enables support for layout qualifier "index" in es profile

Updated extension management in TIntermediate class.

This variable is no longer used, remove.

Enable below features for GL Core version 420:
* layout qualifier "std430"
* storage qualifier "buffer"
* atomic memory functions

Swizzled out operands were added in bbbd9a2a. This was sufficient
for most tests, but we ran into problems with umulExtended and
imulExtended, which have two.

This CL converts the tracking values to vectors so multiple operands
can be supported.

Test: KHR-GLES31.core.shader_bitfield_operation.*
Test: ctest

Fixes issue #2169.

This is causing downstream users compiler errors if they have Werror or other
particularly restrictive flags turned on.

* rework how shader interface block naming rules are handled

* Fixes 2136

According to the spec, shader interfaces (uniform blocks, buffer
blocks, input blocks, output blocks) all should be matched up via
their block names across all compilation units, not instance names.
Also, all block names can be re-used between all 4 interface types
without conflict. This change makes it so all of these blocks are
matched and remapped using block name and not by instance name.
Additional the rule that matched uniform and buffer blocks must
either be anonymous or named (but not nessearily the same name) is
now imposed.

* add warning if instance names differ between matched shader interfaces

* Add test cases from #2137 which is now fixed as well.

* replace some tab characters with spaces

* buffer blocks and uniform blocks now share the same block namespace

Error out assignments to objects of rayQueryEXT type.

Remove unused variables.

This CL removes two unused variables from the initialization code.

Humble fix