Building EarlGrey through carthage with xcode10 fails

Hello all,

When we build EarlGrey through carthage on our CI, with the newest xcode 10 beta, it fails to compile. Is anyone looking into these problems?

```
Exit status of command 'carthage build --platform iOS --derived-data /Users/.../workspace/iOS-Integration_xcode-10-FKPXLIXHF2LZNBLEHI2A3UF7JBJ4MLJB6OW6QZ5JJOQNF722BLWA/XcodeDerivedData --cache-builds' was 1 instead of 0.
*** No cache found for EarlGrey, building with all downstream dependencies
//// Other frameworks
*** Building scheme "EarlGrey" in EarlGrey.xcodeproj
Build Failed
Task failed with exit code 65:
/usr/bin/xcrun xcodebuild -project /Users/..../workspace/iOS-Integration_xcode-10-FKPXLIXHF2LZNBLEHI2A3UF7JBJ4MLJB6OW6QZ5JJOQNF722BLWA/.../Carthage/Checkouts/EarlGrey/EarlGrey.xcodeproj -scheme EarlGrey -configuration Release -derivedDataPath /Users/.../workspace/iOS-Integration_xcode-10-FKPXLIXHF2LZNBLEHI2A3UF7JBJ4MLJB6OW6QZ5JJOQNF722BLWA/XcodeDerivedData/10.0_10L201y/EarlGrey/1.14.0 -sdk iphoneos ONLY_ACTIVE_ARCH=NO CODE_SIGNING_REQUIRED=NO CODE_SIGN_IDENTITY= CARTHAGE=YES archive -archivePath /var/folders/yc/tjq3l5k126158h1f_8hfsn5r0000gn/T/EarlGrey SKIP_INSTALL=YES GCC_INSTRUMENT_PROGRAM_FLOW_ARCS=NO CLANG_ENABLE_CODE_COVERAGE=NO STRIP_INSTALLED_PRODUCT=NO (launched in /Users/..../workspace/iOS-Integration_xcode-10-FKPXLIXHF2LZNBLEHI2A3UF7JBJ4MLJB6OW6QZ5JJOQNF722BLWA/.../Carthage/Checkouts/EarlGrey)

This usually indicates that project itself failed to compile. Please check the xcodebuild log for more details: /var/folders/yc/tjq3l5k126158h1f_8hfsn5r0000gn/T/carthage-xcodebuild.Jr5TTv.log
```

### Used Setup
#### Cartfile.private
```
github "google/EarlGrey"
```

#### Cartfile.resolved
```
github "google/EarlGrey" "1.14.0"
```

#### Carthage command
```
carthage bootstrap --cache-builds --platform iOS
```

#### Terminal settings
Set `xcode-select` to `xcode-beta.app`.

Thanks in advance :-) .

Start by reproducing the Carthage bootstrap using Xcode 10 beta and the EarlGrey 1.14.0 Cartfile.resolved entry. Inspect the referenced carthage-xcodebuild.Jr5TTv.log and the EarlGrey.xcodeproj build output to identify the compilation failure; done means the EarlGrey scheme builds successfully through Carthage on that setup.

Written by the indexing model from the issue text.