When using default cc linker, we will have segfault.
Debugging with `rust-gdb`, the specific error is as follows:
src/string/memcpy.c: No such file or directory.
Only changing linker with `aarch64-linux-musl-gcc`, the
`rust-agent` could be totally statically linked and run successfully.
Fixes: #107
Signed-off-by: Penny Zheng <penny.zheng@arm.com>
The __addtf3, __subtf3 and __multf3 symbols are used by aarch64-musl,
but are not provided by rust compiler-builtins.
For now, the only temporary but functional workaround accepted by rust
communities is to get them from libgcc.
Fixes: #107
Signed-off-by: Penny Zheng <penny.zheng@arm.com>
