[Patch] x86: SETcc/TEST/SETcc -> SETcc/SETcc optimisation
<h3><details><summary>Original Reporter info from Mantis: <small>CuriousKit @CuriousKit</small></summary><small>
- **Reporter name:** J. Gareth Moreton
</small></details></h3>
## Description:
This patch extends the SETcc/TEST/Jcc optimisation to also work with SETcc instead of just Jcc.
## Steps to reproduce:
Apply patch and confirm correct compilation.
## Additional information:
This particular optimisation only appears a few times in the RTL, but the addition to the compiler source is very cheap.
In Sysutils, before:
```
...
btl %eax,TC_$SYSTEM_$$_ALLOWDIRECTORYSEPARATORS(%rip)
setcb %al
testb %al,%al
# Peephole Optimization: J(c)Mov1JmpMov0 -> Set(~c) (partial)
setneb %al
ret
.Lj1274:
...
```
After:
```
...
btl %eax,TC_$SYSTEM_$$_ALLOWDIRECTORYSEPARATORS(%rip)
# Peephole Optimization: J(c)Mov1JmpMov0 -> Set(~c) (partial)
# Peephole Optimization: SETcc/TEST/SETcc -> SETcc
setcb %al
ret
.Lj1274:
...
```
## Mantis conversion info:
- **Mantis ID:** 39271
- **OS:** Microsoft Windows
- **OS Build:** 10 Home
- **Build:** r49621
- **Platform:** i386 and x86_64
- **Version:** 3.3.1
issue