Merge branch 'mbedtls-1.3' into development

* mbedtls-1.3:
  Include changes from the 1.2 branch
  Remove unused headers in o_p_test
  Add countermeasure against cache-based lucky 13
  Make results of (ext)KeyUsage accessible
  Fix missing NULL check in MPI
  Fix detection of getrandom()
  Fix "make install" handling of symlinks
  Fix bugs in programs displaying verify flags

Conflicts:
	Makefile
	include/polarssl/ssl.h
	library/entropy_poll.c
	library/ssl_srv.c
	library/ssl_tls.c
	programs/test/o_p_test.c
	programs/test/ssl_cert_test.c
	programs/x509/cert_app.c
diff --git a/tests/suites/test_suite_mpi.function b/tests/suites/test_suite_mpi.function
index bf4f0b3..134d220 100644
--- a/tests/suites/test_suite_mpi.function
+++ b/tests/suites/test_suite_mpi.function
@@ -8,6 +8,25 @@
  */
 
 /* BEGIN_CASE */
+void mpi_null( )
+{
+    mbedtls_mpi X, Y, Z;
+
+    mbedtls_mpi_init( &X );
+    mbedtls_mpi_init( &Y );
+    mbedtls_mpi_init( &Z );
+
+    TEST_ASSERT( mbedtls_mpi_get_bit( &X, 42 ) == 0 );
+    TEST_ASSERT( mbedtls_mpi_lsb( &X ) == 0 );
+    TEST_ASSERT( mbedtls_mpi_msb( &X ) == 0 );
+    TEST_ASSERT( mbedtls_mpi_size( &X ) == 0 );
+
+exit:
+    mbedtls_mpi_free( &X );
+}
+/* END_CASE */
+
+/* BEGIN_CASE */
 void mpi_read_write_string( int radix_X, char *input_X, int radix_A,
                             char *input_A, int output_size, int result_read,
                             int result_write )