Merge pull request #199 from rust-embedded/weak-symbols

`riscv-rt`: make `abort` weak

riscv-rt/CHANGELOG.md

@@ -15,6 +15,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 
 - Moved all the assembly code to `asm.rs`
 - Use `weak` symbols for functions such as `_mp_hook` or `_start_trap`
+- `abort` is now `weak`, so it is possible to link third-party libraries including this symbol.
 
 ### Removed
 

riscv-rt/src/asm.rs

@@ -337,7 +337,7 @@ trap_handler!(
 #[rustfmt::skip]
 global_asm!(
     ".section .text.abort
-    .global abort
+.weak abort
 abort:  // make sure there is an abort symbol when linking
     j abort"
 );