binderLibTest: better message for status

Turn code like

  ret = ...;
  EXPECT_EQ(OK, ret);

into

  EXPECT_THAT(..., StatusEq(OK));

This avoids declaring a status_t variable every time.

More importantly, the StatusEq matcher prints statusToString() for both the
expected and actual value, leading to much clearer error messages than
status_t codes. Example:

  Value of: server->addRpcClient(android::base::unique_fd())
  Expected: BAD_VALUE
    Actual: -2147483646, FAILED_TRANSACTION

Also fix places where the return value is not checked.

Test: run it

Change-Id: I0c6ee1cedb300b978c6ed7b44fd5da37ba6d7aa7
diff --git a/libs/binder/tests/Android.bp b/libs/binder/tests/Android.bp
index c0f7c99..ec231b2 100644
--- a/libs/binder/tests/Android.bp
+++ b/libs/binder/tests/Android.bp
@@ -63,6 +63,9 @@
         "libbinder",
         "libutils",
     ],
+    static_libs: [
+        "libgmock",
+    ],
     compile_multilib: "32",
     multilib: { lib32: { suffix: "" } },
     cflags: ["-DBINDER_IPC_32BIT=1"],
@@ -101,6 +104,9 @@
         "libbinder",
         "libutils",
     ],
+    static_libs: [
+        "libgmock",
+    ],
     test_suites: ["device-tests", "vts"],
     require_root: true,
 }