Include program counter value in backtrace when -v is passed

[jonas-schievink]

This can help when debugging.

stack backtrace:
   0: 0x000015b0 @ HardFaultTrampoline
      <exception entry>
   1: 0x000008de @ lib::inline::__udf
        at ./asm/inline.rs:172:5
   2: 0x000008de @ __udf
        at ./asm/lib.rs:49:17
   3: 0x000001c8 @ cortex_m::asm::udf
        at [cortex-m-0.7.3]/src/asm.rs:43:5
   4: 0x000001d2 @ _defmt_panic
        at /tmp/app/src/lib.rs:11:5
   5: 0x000001be @ defmt::export::panic
        at /home/japaric/.cargo/git/checkouts/defmt-52fbd7917982cfac/e021e7d/src/export.rs:266:14
   6: 0x000001be @ panic::__cortex_m_rt_main
        at /tmp/app/src/bin/panic.rs:8:5
   7: 0x00000194 @ main
        at /tmp/app/src/bin/panic.rs:6:1
   8: 0x000001dc @ ResetTrampoline
        at [cortex-m-rt-0.6.14]/src/lib.rs:547:26
   9: 0x0000018a @ Reset
        at [cortex-m-rt-0.6.14]/src/lib.rs:550:13

[jonas-schievink]

bors r=jonathanpallant

[bors[bot]]

Build succeeded:

• ci