This shortens the code and reduces the amount of temp regs used by 1.

texm3x2pad knows which register the following texm3x2depth or tex instruction
will use, and it knows that this register is uninitialized. So use it for
temporary storage instead of TMP.

We have 5 temporary registers declared for private use. We can get rid of two
of them.

user32: Invalidate a being removed listbox item before deleting it as it's been done before d2ecb119.

Thanks to Dimitriu Petru for spotting this.