Apply memory decorations from GLSL source to the top-level OpVariable.
Previously, these decorations would only be applied to individual
members. While this is correct behavior, it is more convenient for some
front ends to see the decorations (specifically ReadOnly and WriteOnly)
applied to the whole variable rather than individual members.
It is invalid if the same decoration is applied to the same id multiple
times. This adds a check before adding a decoration that the decoration
is not already in the list. If it is, then the duplicate is not added.
Fixes#3627
For GL_EXT_vulkan_glsl_relaxed. When merging the default uniform block,
there were cases where symbols in the tree wern't updated to match the
new block structure after merging blocks together.
This change traverses the symbol tree and updates any references to the
merged block.
