Multiple memory corruptions in objdump (binuitils-2.30-15ubuntu1)

Dear all,
The following binutils objdump memory corruptions were found by a modified version of the kAFL fuzzer (https://github.com/RUB-SysSec/kAFL). I have attached the crashing inputs and each ASAN report.

Steps to reproduce:

Build current verison of binutils:
```
pull-lp-source binutils
cd binutils-2.30
CC=clang CXX=clang++ CFLAGS="-fsanitize=address -fsanitize-recover=address -ggdb" CXXFLAGS="-fsanitize=address -fsanitize-recover=address -ggdb" LDFLAGS="-fsanitize=address" ./configure
CC=clang CXX=clang++ CFLAGS="-fsanitize=address -fsanitize-recover=address -ggdb" CXXFLAGS="-fsanitize=address
-fsanitize-recover=address -ggdb" LDFLAGS="-fsanitize=address" make
```

Run inputs under ASAN:

```
ASAN_OPTIONS=halt_on_error=false:allow_addr2line=true ./objdump --dwarf-check -C -g -f -dwarf -x $file
```

We can verify those issues for objdump binuitils-2.30-15ubuntu1 (Ubuntu 16.04.4 LTS / sources from "pull-lp-source bintuils").

Credits: Sergej Schumilo, Cornelius Aschermann (both of Ruhr-Universität Bochum)

Best regards,
Sergej Schumilo