Update SDK:s/cmake-startup for next release with cmake included

For the next SDK-Addon release that includes cmake, please update `SDK:s/cmake-startup`.

**Issue:**
abc-shell uses a hardcoded PATH if no PATH environment variable is set. If there is a PATH environment variable, abc-shell will use it without modification. Since most users do not set a custom PATH, `cmake-startup` will override abc-shell's path and render it useless. This needs to be addressed before the release.

**Example:**
```
3. > RAM Disk: > setenv PATH /cmake-amiga/bin
3. > RAM Disk: > sh
/RAM Disk> echo $PATH
/cmake-amiga/bin
```

**Solution:**
One solution would be to set the complete default PATH if there is no PATH env in `cmake-startup`:
```
assign cmake-amiga: SDK:cmake

GetEnv >NIL: *>NIL: PATH
If WARN
setenv PATH /cmake-amiga/bin:/gcc/bin:/SDK/C:/SDK/Local/C:/SDK/Local/newlib/bin:/SDK/Local/clib2/bin:/C:.
Else
setenv PATH /cmake-amiga/bin:${PATH}
EndIf

path ADD cmake-amiga:bin
```