We can use const local variables without capturing.

bug: chromium:681136
Change-Id: I2df60e02920841222b6e63aaa2be3ecbb8d6db2c
Reviewed-on: https://swiftshader-review.googlesource.com/c/21848Reviewed-by: Alexis Hétu <sugoi@google.com>
Tested-by: Takuto Ikuta <tikuta@google.com>