Add device tests for libc functional verification

Add test suite used to debug libc optimized _P functions to the device
tests.

Author: earlephilhower

tests/device/libraries/BSTest/runner.py

@@ -132,7 +132,7 @@ def run_tests(self):
 
     def run_test(self, index):
         self.sp.sendline('{}'.format(index))
-        timeout = 10
+        timeout = 20 # 10
         while timeout > 0:
             res = self.sp.expect(['>>>>>bs_test_start', EOF, TIMEOUT])
             if res == 0: