According to the Vulkan spec:
"fullDrawIndexUint32 specifies the full 32-bit range
 of indices is supported for indexed draw calls when
 using a VkIndexType of VK_INDEX_TYPE_UINT32.
 maxDrawIndexedIndexValue is the maximum index value
 that may be used (aside from the primitive restart
 index, which is always 2^32-1 when the VkIndexType is
 VK_INDEX_TYPE_UINT32). If this feature is supported,
 maxDrawIndexedIndexValue must be 2^32-1; otherwise it
 must be no smaller than 2^24-1."

maxDrawIndexedIndexValue is already set to 2^32-1, so
there's nothing left to do but enable the feature.

Bug: b/145670585
Change-Id: I5f2e554ccd2eb94cd0b0e3c30391b83389200afa
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/38948
Presubmit-Ready: Alexis Hétu <sugoi@google.com>
Reviewed-by: Chris Forbes <chrisforbes@google.com>
Kokoro-Presubmit: kokoro <noreply+kokoro@google.com>
Tested-by: Alexis Hétu <sugoi@google.com>