Use shared variant of dep for packaging

For native modules that have both static and shared variants (e.g.
cc_library), the deps mutator of android_filesystem would always create
a dep to the static variant. This is likely due to the fact that
`AddFarVariationDependencies` creates a dependency on the first variant
of the dep which matches the requested variations. `static` appears
before `shared` in linkMutator, and therefore android_filesystem would
always create a dep to the static variant.

This CL uses `OtherModuleFarDependencyVariantExists` to create a dep to
the shared variant. If a cc_library is listed in `PRODUCT_PACKAGES`, it
always means the shared variant.

Test: go test./filesystem
Test: diff in kati install files of vendor/ before and after this CL
https://diff.googleplex.com/#key=qrY73chVkwff

Change-Id: Iea9d6fde199ef95d43da2c041e2f84e5a7951285
diff --git a/filesystem/filesystem_test.go b/filesystem/filesystem_test.go
index 15c4898..ab63550 100644
--- a/filesystem/filesystem_test.go
+++ b/filesystem/filesystem_test.go
@@ -610,3 +610,22 @@
 	fileList := android.ContentFromFileRuleForTests(t, result.TestContext, partition.Output("fileList"))
 	android.AssertDeepEquals(t, "filesystem with dependencies on different partition", "bin/binfoo\n", fileList)
 }
+
+// If a cc_library is listed in `deps`, and it has a shared and static variant, then the shared variant
+// should be installed.
+func TestUseSharedVariationOfNativeLib(t *testing.T) {
+	result := fixture.RunTestWithBp(t, `
+		android_filesystem {
+			name: "myfilesystem",
+			deps: ["libfoo"],
+		}
+		// cc_library will create a static and shared variant.
+		cc_library {
+			name: "libfoo",
+		}
+	`)
+
+	partition := result.ModuleForTests("myfilesystem", "android_common")
+	fileList := android.ContentFromFileRuleForTests(t, result.TestContext, partition.Output("fileList"))
+	android.AssertDeepEquals(t, "cc_library listed in deps", "lib64/libc++.so\nlib64/libc.so\nlib64/libdl.so\nlib64/libfoo.so\nlib64/libm.so\n", fileList)
+}