Depend all_tests on p256-x86_64_test.

Otherwise the run_tests target sometimes gets confused.

Change-Id: If49e945bf5137c68db4927ab0f9845d25be63bac
Reviewed-on: https://boringssl-review.googlesource.com/12315
Reviewed-by: Steven Valdez <svaldez@chromium.org>
Reviewed-by: David Benjamin <davidben@google.com>
Commit-Queue: David Benjamin <davidben@google.com>
CQ-Verified: CQ bot account: commit-bot@chromium.org <commit-bot@chromium.org>

crypto/ec/CMakeLists.txt

@@ -57,4 +57,4 @@ add_executable(
 target_link_libraries(example_mul crypto)
 target_link_libraries(ec_test crypto)
 target_link_libraries(p256-x86_64_test crypto)
-add_dependencies(all_tests example_mul ec_test)
+add_dependencies(all_tests example_mul ec_test p256-x86_64_test)