better gtest runner for bionic

1. option to run each test in a separate forked process: "--isolate".
2. warnings about slow tests: "--warnline".
3. run multiple tests at the same time: "-j N".

Bug: 17589740
Change-Id: Ife5f4cafec43aa051ad7bd9c9b2b7e2e437db0de
diff --git a/tests/Android.mk b/tests/Android.mk
index 3f5a112..dfb89d2 100644
--- a/tests/Android.mk
+++ b/tests/Android.mk
@@ -223,6 +223,7 @@
     liblog \
 
 bionic-unit-tests_src_files := \
+    gtest_main.cpp \
     atexit_test.cpp \
     dl_test.cpp \
     dlext_test.cpp \
@@ -275,6 +276,9 @@
     libtinyxml2 \
     liblog \
 
+bionic-unit-tests-static_src_files := \
+    gtest_main.cpp \
+
 bionic-unit-tests-static_force_static_executable := true
 
 # libc and libc++ both define std::nothrow. libc's is a private symbol, but this
@@ -297,6 +301,7 @@
 ifeq ($(HOST_OS)-$(HOST_ARCH),$(filter $(HOST_OS)-$(HOST_ARCH),linux-x86 linux-x86_64))
 
 bionic-unit-tests-glibc_src_files := \
+    gtest_main.cpp \
     atexit_test.cpp \
     dlfcn_test.cpp \
     dl_test.cpp \