[Bug target/70713] msp430 interrupt attribute prevents overriding weak symbols

[joe.s+bugzilla at somniumtech dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70713

--- Comment #2 from Joe Seymour <joe.s+bugzilla at somniumtech dot com> ---
Proposed patch: https://gcc.gnu.org/ml/gcc-patches/2016-08/msg01882.html