Generating static objects within a function results in multithread safe
code. This code generates the static objects upon the first execution of the
line which declares the object. This results in high runtime cost for
synchronization and a bigger code size.

Instead introduce a new function uint32_t GetPackedTypeInfo(GLenum type)
which returns a packed representation for the Type class. This
representation is usually returned in a register on the assembly level.
As a result we save constant storage for the TypeInfo object and one
indirection when reading any value from this object. The Type constructor
accepts the packed representation and unpacks it an inline function. For
fields which are not used the compiler also applies dead code
elimination which reduces the cost furthermore.

As a result of this change the cost of GetTypeInfo is reduced by a
factor of 4-5.

Bug: angleproject:2974
Change-Id: I8ed0bf2f09d087fa4cffa04f82e3b7f8c183fe30
Reviewed-on: https://chromium-review.googlesource.com/c/1340221Reviewed-by: Jamie Madill <jmadill@chromium.org>
Commit-Queue: Jamie Madill <jmadill@chromium.org>