Fix import of settings file for relative ExoPlayer paths.

Including ExoPlayer via relative paths currently breaks the import
logic of the common library settings file because it's referenced
from different directories. Fix this by resolving the setting path
to its canonical name.

Issue: #7554
PiperOrigin-RevId: 319043560

common_library_config.gradle

@@ -12,7 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-apply from: "$gradle.ext.exoplayerRoot/constants.gradle"
+apply from: "$gradle.ext.exoplayerSettingsDir/constants.gradle"
 apply plugin: 'com.android.library'
 
 android {

core_settings.gradle

@@ -13,7 +13,7 @@
 // limitations under the License.
 def rootDir = gradle.ext.exoplayerRoot
 if (!gradle.ext.has('exoplayerSettingsDir')) {
-    gradle.ext.exoplayerSettingsDir = rootDir
+    gradle.ext.exoplayerSettingsDir = new File(rootDir).getCanonicalPath()
 }
 def modulePrefix = ':'
 if (gradle.ext.has('exoplayerModulePrefix')) {