Swift: Add a test of Location.qll.

Author: geoffw0

swift/ql/test/library-tests/elements/location/location.expected

@@ -0,0 +1,4 @@
+| file://:0:0:0:0 | UnknownLocation |
+| location.swift:2:1:3:1 | DbLocation |
+| location.swift:2:11:2:14 | DbLocation |
+| location.swift:2:19:3:1 | DbLocation |

swift/ql/test/library-tests/elements/location/location.ql

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+import swift
+
+from Location l
+select l

swift/ql/test/library-tests/elements/location/location.swift

@@ -0,0 +1,3 @@
+
+func test(x: Int) {
+}