Auto merge of #1521 - Wind-River:master_rebase, r=gnzlbg

Fix building error at backtrace

I get this error when builind backtrace:

error[E0308]: mismatched types
  --> /folk/prj-rust-dev/bpang/ala-diab-pb19l/fix_bugs/latest/.cargo/git/checkouts/backtrace-rs-fb1f822361417489/e745627/src/symboli\
ze/dladdr.rs:38:73
   |
38 |                         Some(SymbolName::new(slice::from_raw_parts(ptr, len)))
   |                                                                         ^^^ expected usize, found u64
help: you can convert an `u64` to `usize` and panic if the converted value wouldn't fit

It shows the 'size_t' is expected to be defined as "usize".