Call cl::ResetAllOptionOccurrences() before reparsing LLVM options
Call cl::ResetAllOptionOccurrences() before reparsing LLVM options

This change makes ICompiler::Create check whether options have
previously been parsed, regardless of whether any instances are
currently active, and calls cl::ResetAllOptionOccurrences() when options
are changing. The error handler is also removed when the last compiler
instance is destroyed. These changes fix crashes while running Vulkan
CTS.

googlestadia/llpc,googlestadia/llpc,GPUOpen-Drivers/llpc,GPUOpen-Drivers/llpc,googlestadia/llpc,GPUOpen-Drivers/llpc,GPUOpen-Drivers/llpc,googlestadia/llpc,googlestadia/llpc,GPUOpen-Drivers/llpc