broadcom/compiler: Emit better code for x != 0 and x == 0
There doesn't seem to be an algebraic optimization pass in the Broadcom compiler that will simplify (x ^ 0). Since x != 0 is equivalent to i2b(x), detect this case and emit the same code.
This prevents (hypothetical) regressions when i2b is always lowered to ine.
This commit is peeled out from !15121 (merged).