[cxx-interop] Test importing Glibc with cxx-interop enabled.

Author: zoecarver

test/Interop/Cxx/stdlib/include-glibc.swift

@@ -0,0 +1,15 @@
+// RUN: %target-run-simple-swift(-Xfrontend -enable-cxx-interop)
+
+// REQUIRES: executable_test
+// REQUIRES: OS=linux-gnu
+
+import Glibc
+import StdlibUnittest
+
+var GlibcTests = TestSuite("GlibcTests")
+
+GlibcTests.test("abs") {
+  expectEqual(42, abs(-42))
+}
+
+runAllTests()