Refuse to use use exiftool from c:\windows instead of crashing

[hvdwolf]

Version (please complete the following information):

• OS: Windows
• Version: 7/8/10
• windows exe

Describe the bug
This is a followup of bug #110, where later on it was mentioned that exiftool.exe in c:\windows would also crash JTG.
The "bug" is that, to be able to use exiftool from c:\windows, a program needs local admin access. I don't want my program to have local admin.

To fix: If exiftool is found in c:\windows, then simply refuse to use it and tell the user about it.

[hvdwolf]

Addition: If it is already working for a user, because he/she is local admin and can use it as local admin, then leave it as is.