Set skipInstall to false to avoid debug flag

The flag ´-lrobovm-debug´ makes the validation service fail when trying to upload the IPA to Apple.
Fails with message "non public symbols in exc_server"

Flag is set if skipInstall is true at:
https://github.com/robovm/robovm/blob/36b4fd955a8acbae0459550d324c5c70d996ee6c/compiler/src/main/java/org/robovm/compiler/target/AbstractTarget.java#L98