bionic tests: use GTEST_SKIP.

Also be a bit more to the point in our messages, focusing on "why" not
"what".

Test: ran tests
Change-Id: I297806c7a102bd52602dcd2fcf7a2cd34aba3a11
diff --git a/tests/grp_pwd_test.cpp b/tests/grp_pwd_test.cpp
index eb8fe2a..b46839b 100644
--- a/tests/grp_pwd_test.cpp
+++ b/tests/grp_pwd_test.cpp
@@ -138,17 +138,13 @@
 
 #else // !defined(__BIONIC__)
 
-static void print_no_getpwnam_test_info() {
-  GTEST_LOG_(INFO) << "This test is about uid/username translation for Android, which does nothing on libc other than bionic.\n";
-}
-
 static void check_get_passwd(const char* /* username */, uid_t /* uid */, uid_type_t /* uid_type */,
                              bool /* check_username */) {
-  print_no_getpwnam_test_info();
+  GTEST_SKIP() << "bionic-only test";
 }
 
 static void check_get_passwd(const char* /* username */, uid_t /* uid */, uid_type_t /* uid_type */) {
-  print_no_getpwnam_test_info();
+  GTEST_SKIP() << "bionic-only test";
 }
 
 #endif
@@ -311,7 +307,7 @@
 
   expect_ids(uids);
 #else
-  print_no_getpwnam_test_info();
+  GTEST_SKIP() << "bionic-only test";
 #endif
 }
 
@@ -382,16 +378,12 @@
 
 #else // !defined(__BIONIC__)
 
-static void print_no_getgrnam_test_info() {
-  GTEST_LOG_(INFO) << "This test is about gid/group_name translation for Android, which does nothing on libc other than bionic.\n";
-}
-
 static void check_get_group(const char*, gid_t, bool) {
-  print_no_getgrnam_test_info();
+  GTEST_SKIP() << "bionic-only test";
 }
 
 static void check_get_group(const char*, gid_t) {
-  print_no_getgrnam_test_info();
+  GTEST_SKIP() << "bionic-only test";
 }
 
 #endif
@@ -501,7 +493,7 @@
   check_group(grp[0], "root", 0);
   check_group(grp[1], "system", 1000);
 #else
-  print_no_getgrnam_test_info();
+  GTEST_SKIP() << "bionic-only test";
 #endif
 }
 
@@ -521,7 +513,7 @@
   check_group(grp[0], "root", 0);
   check_group(grp[1], "system", 1000);
 #else
-  print_no_getgrnam_test_info();
+  GTEST_SKIP() << "bionic-only test";
 #endif
 }
 
@@ -561,7 +553,7 @@
 
   expect_ids(gids);
 #else
-  print_no_getgrnam_test_info();
+  GTEST_SKIP() << "bionic-only test";
 #endif
 }
 
@@ -590,7 +582,7 @@
 
   TestAidNamePrefix("/vendor/etc/passwd");
 #else
-  print_no_getpwnam_test_info();
+  GTEST_SKIP() << "bionic-only test";
 #endif
 }
 
@@ -602,6 +594,6 @@
 
   TestAidNamePrefix("/vendor/etc/group");
 #else
-  print_no_getgrnam_test_info();
+  GTEST_SKIP() << "bionic-only test";
 #endif
 }