Use a global gtest isolation runner rather than the custom one in
bionic.
Test: Ran all unit tests and verified same behavior before and after.
Change-Id: I24a7cf17cf8e018d0f51969c64b53ce9059cc779
Also add another test for dlsym(RTLD_NEXT, ..)
Bug: http://b/33106624
Test: run bionic-unit-tests-glibc and bionic-unit-tests
Change-Id: I340165d66bf2360b0e3273d3561a08cb5e7bd025
Replace references to ANDROID_DATA enviroment variable with references
to g_testlib_root.
Bug: http://b/22182538
Test: build and run bionic-unit-tests --gtest_filter=dl*:Dl*
Test: make cts && cts-tradefed run singleCommand cts --skip-preconditions -m CtsBionicTestCases
Change-Id: I5667e991551cec55b9b664f2f0063039671ff34b
