New versions of Clang warn:
```
glslang/MachineIndependent/Constant.cpp(216,114):
error: overflow in expression; result is -9223372036854775808 with type 'long long' [-Werror,-Winteger-overflow]
else if (rightUnionArray[i].getI64Const() == -1 && leftUnionArray[i].getI64Const() == (long long)-0x8000000000000000ll)
^
glslang/MachineIndependent/Constant.cpp(217,61):
error: overflow in expression; result is -9223372036854775808 with type 'long long' [-Werror,-Winteger-overflow]
newConstArray[i].setI64Const((long long)-0x8000000000000000ll);
^
2 errors generated.
```
Using LLONG_MIN instead avoids the problem. I think it's also more
clear, and the code for EOpMod further down already does this.
7341a21b34