* Improve size optimizations when compiling material
This changes the behavior of the size optimizer in matc (-S), but
only for GLSL and MSL. With this change we gain a ~65% size reduction
on a lit material compiled for OpenGL. To get those gains we generate
extra SPIRV debug information to preserve variable names and better
utilize the line dictionary. Unfortunately this break the SPIRV
optimizer so we skip it and instead rely on a simple DCE pass provided
by glslang. We also enhance the whitespace removal pass of the GLSL
minifier to move lone { and } to the previous line, which avoids
generating an extra index in each shader variant. Each index being
at least as big as the character itself, this is quite wasteful.
When generating SPIRV for Vulkan, we rely on spirv-opt for size
optimizations as before.
4a116e6791