bionic/tests: migrate gethostbyname bionic test from system/extra to bionic/tests

this change migrate the gethostbyname test defined in the old file
system/extras/tests/bionic/libc/common/test_gethostbyname.c
to the new place bionic/tests/netdb_test.cpp

Change-Id: I342171090f681581fb54d68ea4a09adf61f52081
Signed-off-by: Yongqin Liu <yongqin.liu@linaro.org>
diff --git a/tests/netdb_test.cpp b/tests/netdb_test.cpp
index 33f6c01..cc08715 100644
--- a/tests/netdb_test.cpp
+++ b/tests/netdb_test.cpp
@@ -55,3 +55,13 @@
   ASSERT_STREQ("::", tmp);
   ASSERT_EQ(EAI_FAMILY, getnameinfo(sa, too_little, tmp, sizeof(tmp), NULL, 0, NI_NUMERICHOST));
 }
+
+TEST(netdb, gethostbyname) {
+  hostent* hent = gethostbyname("localhost");
+  ASSERT_TRUE(hent != NULL);
+  ASSERT_EQ(hent->h_addrtype, AF_INET);
+  ASSERT_EQ(hent->h_addr[0], 127);
+  ASSERT_EQ(hent->h_addr[1], 0);
+  ASSERT_EQ(hent->h_addr[2], 0);
+  ASSERT_EQ(hent->h_addr[3], 1);
+}