disable ubsan (integer_overflow)

Due to the bug in the current stringstream, CodeWriter fails to write
non-ascii characters when ubsan is on.

Bug: 174366536
Test: aidl_unittests
Test: aidlcpp system/iorap/binder/com/google/android/startop/iorap/IIorap.aidl
Change-Id: I7f9ceb69b0652f56ccfcb19fa0f24c5ceed49b65
2 files changed