idc: Fix quoting of .idl file

Call quotePath() on the idlfile inside dumpIdl() when building
the command to run for .exe files instead of quoting it before
passing it to dumpIdl().

Task-number: QTBUG-55332
Change-Id: Iae934e960d94fe1f9b469ca57f9fba2c74ee108c
Reviewed-by: Karsten Heimrich <karsten.heimrich@qt.io>