Normalize system directories from the interface target property

The input dir being tested is normalized, so ensure that the entries
in the vector are normalized too (eg no trailing slash).
CTest: Fix GTM coverage parsing line offset bug

In cmParseGTMCoverage::ReadMCovFile, initialize the lineoffset variable.
Also set lastoffset only if the function is found (thanks to Bill
Hoffman).
Merge topic 'normalize-system-includes-check'

5e15f39 Normalize system directories from the interface target property
Merge topic 'ctest-gtm-coverage-fileoffset-bug'

782eba3 CTest: Fix GTM coverage parsing line offset bug