porttrace.tcl: renamed variable tracelib
porttrace.tcl: renamed variable tracelib

“tracelib" is a command being used in the file.
"tracelib" is also being used as a variable name.
Renamed “tracelib" variable to “darwintracepath" to make more sense.
neverpanic/macports-base,neverpanic/macports-base,macports/macports-base,macports/macports-base,danchr/macports-base,danchr/macports-base