Disable fast math for gl_Position
Disable fast math for gl_Position

I accidentally disabled the existing fix to disable fast math for
gl_Position in my change "Switched LowerGlobal to use builder methods
for input/output". This commit re-enables it.

Change-Id: I175e8bb5ffe0611fecbe2a85a104b526d9cf7d80

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