[Index] Always skip invalid locations outside of modules
[Index] Always skip invalid locations outside of modules

There's a number of paths that end up calling into `initIndexSymbol`
that may or may not have checked that the given location is actually
valid. Add an extra check within the method to guarantee we only output
0:0 locations when indexing modules.

Resolves rdar://98645486.

roambotics/swift,roambotics/swift,roambotics/swift,apple/swift,apple/swift,apple/swift,roambotics/swift,apple/swift,apple/swift,apple/swift,roambotics/swift,roambotics/swift